Synonyms for certain Found 4 synonyms across 3 meanings for “certain”. definite but not specified or identified (adj) certain(a) having or feeling no doubt or uncertainty (adj) certain(p)sure established irrevocably (adj) sealed Explore Related Words Rhymes with certainSynonyms for certain(a)Synonyms for certain(p)Synonyms for sureSynonyms for sealed Synonym Finder | Rhyme Finder | Poetry Editor