dedication has 4 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 ceremony in which something (as a building) is dedicated to some goal or purpose
Synonyms, antonyms and the broader and narrower relations for dedication come from Princeton University’s WordNet. Full sources and licences.
a message that makes a pledge
a short message (as in a book or musical work or on a photograph) dedicating it to someone or something
the act of binding yourself (intellectually or emotionally) to a course of action
“his long commitment to public service”