alienation 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. 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.
the feeling of being alienated from other people
separation resulting from hostility
Synonyms, antonyms and the broader and narrower relations for alienation come from Princeton University’s WordNet. Full sources and licences.
(law) the voluntary and absolute transfer of title and possession of real property from one person to another
“the power of alienation is an essential ingredient of ownership”
the action of alienating; the action of causing to become unfriendly
“his behavior alienated the other students”