subservient has 4 distinct synonyms spread across 2 of its 3 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
serving or acting as a means or aid
“instrumental in solving the crime”
abjectly submissive; characteristic of a slave or servant
“slavish devotion to her job ruled her life”
1 of the 3 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for subservient.
Synonyms, antonyms and the broader and narrower relations for subservient come from Princeton University’s WordNet. Full sources and licences.