specialisation has 5 distinct synonyms spread across 3 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.
(biology) the structural adaptation of some body part for a particular function
“cell differentiation in the developing embryo”
the act of specializing; making something suitable for a special purpose
Synonyms, antonyms and the broader and narrower relations for specialisation come from Princeton University’s WordNet. Full sources and licences.
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 special line of work you have adopted as your career
“his specialization is gastroenterology”