Synonyms of unofficial in English:

unofficial


See US English definition of unofficial

See UK English definition of unofficial

adjective

1‘unofficial figures put the death toll at over 300’

SYNONYMS
unauthenticated, unconfirmed, uncorroborated, unsubstantiated, unratified
undocumented, off the record
unauthorized, unsanctioned, uncertified
ANTONYMS

official, confirmed

2‘he took it on himself to act as chairman of an unofficial committee’

SYNONYMS
informal, casual
unauthorized, unsanctioned, unaccredited
wildcat
ANTONYMS

official, formal