crown has 15 distinct synonyms spread across 9 of its 16 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 Crown (or the reigning monarch) as the symbol of the power and authority of a monarchy
“the colonies revolted against the Crown”
the part of a tooth above the gum that is covered with enamel
a wreath or garland worn on the head to signify victory
an ornamental jeweled headdress signifying sovereignty
the part of a hat (the vertex) that covers the crown of the head
(dentistry) dental appliance consisting of an artificial crown for a broken or decayed tooth
“tomorrow my dentist will fit me for a crown”
Synonyms, antonyms and the broader and narrower relations for crown come from Princeton University’s WordNet. Full sources and licences.
form the topmost part of
“A weather vane crowns the building”
put an enamel cover on
“crown my teeth”