siren has 4 distinct synonyms spread across 1 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 woman who is considered to be dangerously seductive
Synonyms, antonyms and the broader and narrower relations for siren come from Princeton University’s WordNet. Full sources and licences.
a warning signal that is a loud wailing sound
an acoustic device producing a loud often wailing sound as a signal or warning
eellike aquatic North American salamander with small forelimbs and no hind limbs; have permanent external gills