employment has 8 distinct synonyms spread across 4 of its 4 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. Its one recorded opposite is unemployment.
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 state of being employed or having a job
“they are looking for employment”
the act of giving someone a job
the act of using
“he warned against the use of narcotic drugs”
Synonyms, antonyms and the broader and narrower relations for employment come from Princeton University’s WordNet. Full sources and licences.