Origin: Latin suffix -al
Informal has 5 different meanings across 1 category:
not formal
"conservative people unaccustomed to informal dress"
"an informal free-and-easy manner"
"an informal gathering of friends"
used of spoken and written language
"The informal tone of his emails made him seem much more approachable to new colleagues."
Not formal or ceremonious.
"The team decided to keep their meeting informal so everyone could relax and share ideas freely."
In plain English: Informal means casual and relaxed, not following strict rules or formal procedures.
"They decided to have an informal chat over coffee without any official agenda."
Informal is a straightforward combination of the prefix in- and the word formal, created to mean not following established rules or conventions. It entered English as a direct opposite to describe relaxed behavior or language that lacks strict structure.