walk out has 1 distinct synonym spread across 1 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.
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.
leave abruptly, often in protest or anger
“The customer that was not served walked out”
Synonyms, antonyms and the broader and narrower relations for walk out come from Princeton University’s WordNet. Full sources and licences.
leave suddenly, often as an expression of disapproval
“She walked out on her husband and children”