What ocular invention got its name
because its double-convex shape resembled a lentil?
Etymology, Etymology, and more Etymology
as well as grammar, usage, euphemism, slang, jargon, semantics, linguistics, neologism, idiom, cant, and argot.

The critically-acclaimed board game
MooT
consists of tough questions about the nuances of the English language.
Answer:
the lens
Eyeglasses were called
lenses because their double-convex shape
resembles a lentil seed. Note: In Latin the word lens means "lentil" and oculus means "eye."
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