appointment has 7 distinct synonyms spread across 4 of its 6 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.
the act of putting a person into a non-elective position
“the appointment had to be approved by the whole committee”
a meeting arranged in advance
“she asked how to avoid kissing at the end of a date”
(usually in the plural) furnishings and equipment (especially for a ship or hotel)
the job to which you are (or hope to be) appointed
“he applied for an appointment in the treasury”
(law) the act of disposing of property by virtue of the power of appointment
“she allocated part of the trust to her church by appointment”
Synonyms, antonyms and the broader and narrower relations for appointment come from Princeton University’s WordNet. Full sources and licences.