CERTAIN Synonyms: 186 Similar and Opposite Words - Merriam-Webster
https://www.merriam-webster.com/thesaurus/certain
WEBSynonyms for CERTAIN: one, some, unnamed, unspecified, anonymous, specific, unidentified, given; Antonyms of CERTAIN: known, named, specified, uncertain, doubtful, unsure, dubious, hesitant.
DA: 38 PA: 15 MOZ Rank: 84