Synonyms of informal

Adjective

1. informal (vs. formal), casual, everyday, daily, free-and-easy, casual, folksy, unceremonious, unceremonial, informal

usage: not formal; "conservative people unaccustomed to informal dress"; "an informal free-and-easy manner"; "an informal gathering of friends"

2. informal, loose, unofficial (vs. official)

usage: not officially recognized or controlled; "an informal agreement"; "a loose organization of the local farmers"

3. informal (vs. formal), colloquial, conversational, common, vernacular, vulgar, epistolary, epistolatory, slangy, subliterary, unliterary, nonliterary, informal, unrhetorical

usage: used of spoken and written language

4. cozy, intimate, informal, friendly (vs. unfriendly)

usage: having or fostering a warm or friendly and informal atmosphere; "had a cozy chat"; "a relaxed informal manner"; "an intimate cocktail lounge"; "the small room was cozy and intimate"

Definition and meaning of informal (Dictionary)