stage has 10 distinct synonyms spread across 7 of its 10 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.
any distinct time period in a sequence of events
“we are in a transitional stage in which many former ideas must be revised or rejected”
a specific identifiable position in a continuum or series or especially in a process
“a remarkable degree of frankness”
a large platform on which people can stand and can be seen by an audience
“he clambered up onto the stage and got the actors to help him into the box”
the theater as a profession (usually `the stage')
“an early movie simply showed a long kiss by two actors of the contemporary stage”
a large coach-and-four formerly used to carry passengers and mail on regular routes between towns
“we went out of town together by stage about ten or twelve miles”
a section or portion of a journey or course
“then we embarked on the second stage of our Caribbean cruise”
any scene regarded as a setting for exhibiting or doing something
“All the world's a stage”
a small platform on a microscope where the specimen is mounted for examination
Synonyms, antonyms and the broader and narrower relations for stage come from Princeton University’s WordNet. Full sources and licences.