passive has 3 distinct synonyms spread across 3 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 active.
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.
expressing that the subject of the sentence is the patient of the action denoted by the verb
“academics seem to favor passive sentences”
the voice used to indicate that the grammatical subject of the verb is the recipient (not the source) of the action denoted by the verb
“`The ball was thrown by the boy' uses the passive voice”
Synonyms, antonyms and the broader and narrower relations for passive come from Princeton University’s WordNet. Full sources and licences.