ahead has 12 distinct synonyms spread across 6 of its 8 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is back.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
ahead of time; in anticipation
“when you pay ahead (or in advance) you receive a discount”
leading or ahead in a competition
“the horse was three lengths ahead going into the home stretch”
having the leading position or higher score in a contest
“he is ahead by a pawn”
2 of the 8 recorded senses carry no synonym, antonym or related term, so they are not shown above. Every sense, with its definition and examples, is on the full entry for ahead.
Synonyms, antonyms and the broader and narrower relations for ahead come from Princeton University’s WordNet. Full sources and licences.