facility has 6 distinct synonyms spread across 3 of its 5 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.
a building or place that provides a particular service or is used for a particular industry
“the assembly plant is an enormous facility”
Synonyms, antonyms and the broader and narrower relations for facility come from Princeton University’s WordNet. Full sources and licences.
skillful performance or ability without difficulty
“his quick adeptness was a product of good design”
a natural effortlessness
“they conversed with great facility”
something designed and created to serve a particular function and to afford a particular convenience or service
“catering facilities”
a service that an organization or a piece of equipment offers you
“a cell phone with internet facility”