turning point has 4 distinct synonyms spread across 2 of its 2 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.
an event marking a unique or important historical change of course or one on which important developments depend
“the agreement was a watershed in the history of both nations”
the intersection of two streets
Synonyms, antonyms and the broader and narrower relations for turning point come from Princeton University’s WordNet. Full sources and licences.
“standing on the corner watching all the girls go by”