moment has 9 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.
a particular point in time
“the moment he arrived the party began”
at this time
“the disappointments of the here and now”
having important effects or influence
“decisions of great consequence are made by the president himself”
a turning force produced by an object acting at a distance (or a measure of that force)
the n-th moment of a distribution is the expected value of the n-th power of the deviations from a fixed value
Synonyms, antonyms and the broader and narrower relations for moment come from Princeton University’s WordNet. Full sources and licences.