lens has 6 distinct synonyms spread across 4 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 transparent optical device used to converge or diverge transmitted light and to form images
Synonyms, antonyms and the broader and narrower relations for lens come from Princeton University’s WordNet. Full sources and licences.
genus of small erect or climbing herbs with pinnate leaves and small inconspicuous white flowers and small flattened pods: lentils
(metaphor) a channel through which something can be seen or understood
“the writer is the lens through which history can be seen”
biconvex transparent body situated behind the iris in the eye; its role (along with the cornea) is to focus light on the retina
electronic equipment that uses a magnetic or electric field in order to focus a beam of electrons