advantage has 2 distinct synonyms spread across 2 of its 4 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 disadvantage.
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.
the quality of having a superior or more favorable position
“the experience gave him the advantage over me”
(tennis) first point scored after deuce
give an advantage to
“This system advantages the rich”
Synonyms, antonyms and the broader and narrower relations for advantage come from Princeton University’s WordNet. Full sources and licences.