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Why Do Children Create Secret Languages? | Glossart Languages
Why do children invent secret words and private codes with siblings or friends? Discover how language creates belonging, group identity and emotional connection.
Evangelia Perifanou
9/16/20269 min read
Why Do Children Create Secret Languages? | Glossart Languages
Two children are sitting together, whispering and laughing. They use strange words that nobody else seems to understand. A familiar word has been shortened, another has been pronounced backwards, and a completely new expression has appeared from nowhere.
When an adult asks what they are saying, the children smile.
“It’s our language.”
Secret languages can appear between siblings, twins, close friends or members of the same group. Sometimes they are simple codes: children replace certain letters, reverse syllables or give ordinary objects imaginary names. In other cases, they develop expressions whose meaning comes from shared games, memories and jokes.
These private ways of speaking may look like nothing more than entertainment. However, they reveal something important about human communication: we use language not only to exchange information, but also to decide who belongs.
What is a secret language?
A secret language does not necessarily need a complete grammar or an extensive dictionary. It can be any shared communication system that is understood mainly—or only—by the people who created it.
Children might:
Change the beginning or ending of familiar words.
Use a made-up word for a particular person or object.
Speak with an unusual rhythm or voice.
Reverse sounds or syllables.
Replace words with numbers, symbols or gestures.
Give ordinary expressions a private meaning.
Build vocabulary from shared jokes and experiences.
For example, two siblings might call the space behind the sofa the moon, even though it has nothing to do with space. The expression makes sense to them because of a game they once played there.
To everybody else, the phrase “Let’s go to the moon” sounds mysterious. To the children, it carries an entire memory.
Why do children enjoy making up words?
Children do not experience language as a fixed system that must never be touched. They experiment with it.
They change sounds, create rhymes and deliberately pronounce words incorrectly because the result is funny. They combine parts of different words or invent names for imaginary creatures. This is one way of exploring how language works.
If changing one sound produces a different word, what happens if they change all the sounds? Can an object have more than one name? Can a word mean something simply because two people agree that it does?
Without realising it, children are discovering one of the central principles of language: words have meaning because communities share them.
There is no natural reason why a particular animal must be called a dog in English, perro in Spanish, chien in French or σκύλος in Greek. Each word works because a group of speakers recognises and uses it.
When two children decide that their invented word mipo means “Come and help me,” they are creating a tiny linguistic community of their own.
A private language creates a private world
Imagine two children who regularly build houses from blankets. Over time, the entrance becomes the tunnel, the biggest cushion becomes the mountain and the box where they keep their toys becomes the treasure room.
Gradually, their game develops its own vocabulary.
The words are meaningful because they belong to a shared world. Someone who has never entered the game may understand the individual words but still fail to understand what the children mean.
This is also true in adult communication. Families, couples, friends and professional groups often develop expressions that outsiders cannot fully understand. A single word may refer to a long story, an embarrassing moment or an old joke.
The vocabulary becomes a form of shared history.
Children’s secret languages make this process especially visible. They show us how quickly language can become connected to relationships, memories and identity.
Language answers the question “Who are we?”
When children create a private code, they are not only deciding what words mean. They are also defining the boundaries of a group.
People who understand the code are inside. People who do not understand it are outside.
This does not always mean that children are deliberately trying to exclude others. Sometimes the pleasure simply comes from sharing something special with a particular person. The language becomes a small sign of trust:
“You know what I mean because you know me.”
Language has always helped people express who they are and where they belong. Accent, vocabulary, pronunciation and even small conversational habits can connect us to a family, region, generation or social group. The Council of Europe notes that languages can symbolise identity and allow speakers to signal aspects of that identity to others.
A secret language is a small but powerful example of this relationship. It allows children to create a collective identity: not only “I,” but “we.”
Why do siblings and close friends develop these codes?
Secret languages are more likely to grow when children spend a great deal of time together.
Siblings may share the same routines, games and family experiences. Close friends may spend hours inventing stories or talking about things that matter only to them. The more experiences two people share, the easier it becomes to communicate with fewer explanations.
A single look may replace an entire sentence. A made-up word may represent something that would take several sentences to explain to another person.
Efficiency can therefore be part of the process. But emotional closeness matters too. The private code becomes proof of the relationship.
Children may enjoy the feeling that they have created something that belongs to them rather than something given to them by adults. Adults usually decide the names of objects, the rules of grammar and the acceptable ways of speaking. A secret language gives children some control.
For once, they are the experts.
What about the “secret languages” of twins?
Twins are often associated with private forms of communication. The term cryptophasia is sometimes used to describe a way of speaking developed between twins that other people find difficult to understand.
However, the idea is often exaggerated in popular culture.
In many cases, twins have not created a completely new language with an independent grammatical system. Instead, they may imitate each other’s immature pronunciation, simplify the same words or develop expressions based on the language they hear around them. Because they understand each other’s habits and spend so much time together, their speech can become mutually intelligible while remaining unclear to adults.
A review of autonomous languages among twins found that these systems often contain modified forms of the adult language, new words and sound-based expressions. They also tend to disappear as children become more involved in communication with a wider community.
This distinction matters. A private way of speaking can be imaginative and meaningful without being a completely separate language.
Is a secret language a sign of language delay?
Usually, playful codes and invented words are not automatically a reason for concern. Wordplay can show creativity, social awareness and an emerging understanding of how language functions.
What matters is the child’s overall communication.
Can the child communicate with people outside the private relationship? Are their speaking and comprehension skills developing appropriately? Can they make themselves understood in the language used at home or school?
If twins or siblings communicate almost exclusively through speech that other people cannot understand, or if parents have concerns about their general language development, it may be helpful to speak with a paediatrician or speech and language professional.
The existence of a private code is not, by itself, a diagnosis. It should be considered alongside the child’s broader communication abilities.
Secret languages are about creativity but also rules
A private language may sound chaotic to an outsider, but children often give it rules.
Perhaps every word must begin with the same sound. Perhaps syllables need to be reversed. Perhaps an extra sound must be inserted after every vowel. When another child makes a mistake, the creators may immediately correct them:
“No, that’s not how we say it!”
This tells us something fascinating. Children do not only invent words; they also notice patterns. They understand that a shared communication system needs consistency.
A code works only if the other person can interpret it. If the rules change every few seconds, communication becomes impossible.
Through creating a language, children may experiment with sounds, word structure, meaning and conversational cooperation. They become both speakers and designers of the system.
The emotional power of being understood
One of the deepest pleasures of a secret language may be the feeling of being understood without having to explain everything.
Close relationships often develop linguistic shortcuts. A particular phrase can recall an entire holiday. A nickname can carry years of affection. A deliberately mispronounced word may survive in a family long after the child who created it has grown up.
The expression may sound meaningless to an outsider. Inside the relationship, it holds emotion.
This helps explain why people sometimes continue using childhood words in adulthood. The words may be unnecessary from a practical perspective, but they preserve a connection with a person, place or earlier version of themselves.
A private word can function almost like a small container for memory.
When belonging becomes exclusion
Secret languages can strengthen relationships, but they can also be used to exclude.
A group of children may intentionally speak in code so that another child feels confused or unwanted. What creates belonging for one group can produce isolation for someone else.
This is another reflection of how language works in society. Slang, specialist terminology, accents and cultural references can connect members of a community. At the same time, they can make outsiders feel that they do not have access to the conversation.
Children may not always recognise the emotional effect of this behaviour. An adult can acknowledge the fun of inventing a code while also helping them notice when it is being used unkindly.
The problem is not the secret language itself. The important question is what the children are doing with it.
Are they creating and playing or deliberately humiliating someone who cannot understand?
Do multilingual children create secret languages differently?
Children who grow up with more than one language already understand that an idea can be expressed in different ways. They may borrow words from several languages, combine them creatively or use one language for a particular character or game.
This does not mean that they are confused.
Multilingual speakers often make sophisticated choices about which language, word or expression best fits a situation. Children may also notice that changing languages can change who understands the conversation.
For example, siblings might use one language with their parents and another when playing together. They may attach certain emotions, memories or roles to each language. Their private expressions can emerge from this rich linguistic environment.
A multilingual child’s invented code might therefore contain sounds and patterns from several languages. Rather than treating this creativity as a mistake, adults can become curious about how the system works.
What secret languages teach us about real languages
A child’s invented code and a natural language are not the same thing. Natural languages are complex systems that develop across communities and generations.
Nevertheless, secret languages reveal several basic truths about communication:
Meanings must be shared.
Patterns help speakers understand one another.
Language changes through use.
New words emerge when people need them.
Relationships influence the way people speak.
Language can include some people and exclude others.
Speaking is connected to identity as well as information.
These principles remain visible throughout our lives.
Teenagers develop slang. Friends repeat expressions from shared experiences. Colleagues use professional vocabulary. Online communities create abbreviations, memes and phrases that may be incomprehensible to newcomers.
Adults have secret languages too. We simply give them different names.
Can invented languages help children learn another language?
Creating a code can become an interesting language-learning activity.
Children can invent names for imaginary objects, create rules for changing words or design a language for a fictional country. They can then explain the system to another person.
This encourages them to think about questions such as:
How are words formed?
How do we show the past?
Does the adjective come before or after the noun?
How do people ask questions?
Are there formal and informal ways of speaking?
Does the language have words that cannot be translated easily?
Older children can compare their invented system with languages they already know. They may begin to notice that languages organise meaning differently.
The purpose is not to create a perfect language. It is to help learners look at real languages with greater curiosity.
Should adults join the secret language?
Sometimes children want adults to participate. At other times, the whole point is that adults cannot understand.
Both reactions are natural.
A parent or teacher can show interest without demanding access:
“That sounds like an interesting language. Does it have any rules?”
“How do you say ‘friend’?”
“Can you teach me one word, or is it completely secret?”
These questions recognise the child’s creativity while allowing them to maintain ownership of the game.
If they decide to teach the language, the adult becomes the learner and the child becomes the expert. That reversal can be especially motivating for a child who feels less confident when learning a language at school.
Language is more than words
Why do children create secret languages?
They create them because sounds are fun to manipulate. Because inventing rules is exciting. Because a private code gives them independence. Because shared words preserve shared memories.
Most importantly, they create them because language can turn a relationship into a community.
A secret language says:
“We made this.”
“We understand each other.”
“This belongs to us.”
That desire does not disappear when childhood ends. Human beings continue to use accents, nicknames, slang, professional terms, jokes and familiar expressions to create connection. Every group develops small linguistic signs that reveal who shares its history.
A child whispering an invented word to a friend is experimenting with one of language’s oldest social powers: its ability to create a sense of we.
A final thought from Glossart Languages
At Glossart Languages, we see language as more than vocabulary and grammar. Every language is also a way of entering relationships, communities and new parts of ourselves.
Children’s secret languages remind us that communication becomes meaningful when it is shared. A word does not need to appear in a dictionary to carry emotion. Sometimes it matters simply because one particular person understands it.
Perhaps that is the real secret: language does not only describe the world around us.
It also helps us decide who we are inside it and who we want beside us.
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