Informal speech is a type of language that is not formal or official. It is often characterized by the use of SLANG and colloquialisms. The two crossword solutions for informal speech are SLANG (5 letters) and TALK (4 letters). SLANG is a type of informal language that is used in everyday conversation and is often seen as humorous or irreverent. TALK is another term for conversation, which is an informal way of communicating with others.