What is the prefixes to informal?

There isn't a specific prefix that directly means "informal." However, depending on the context, you could use prefixes to create words that convey a similar meaning. Here are a few options:

For less formal or less structured:

* Un-: This prefix can be used to indicate the opposite of something, making "unformal" a potential synonym for "informal." However, this word is not commonly used in English.

* Semi-: This prefix suggests something is partially formal, or a mixture of formal and informal. For example, "semi-formal" is a common term for a dress code.

For more casual or relaxed:

* Non-: Similar to "un-," this prefix can indicate the absence of something, suggesting "non-formal" could be used. However, it's not a standard term.

* In-: While not directly related to formality, this prefix can be used to create words that imply a lack of structure or rigidity, such as "informal" or "intimate."

Alternatives to Prefixes:

* Informal is generally the most widely used and understood word for this concept.

* Casual is another common term, especially when referring to dress, language, or social situations.

* Relaxed can also be used, emphasizing a lack of formality and tension.

* Friendly suggests a warm and welcoming atmosphere, often associated with informality.

Ultimately, the best word to use depends on the specific context and the nuance you want to convey.