full-time has no recorded synonym. 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. Its 2 recorded opposites are part-time, half-time.
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.
for the entire time appropriate to an activity
“a full-time job”
for the standard number of hours
“she works full-time”
Synonyms, antonyms and the broader and narrower relations for full-time come from Princeton University’s WordNet. Full sources and licences.