niche (n.)

1610s, "shallow recess in a wall," from French niche "recess (for a dog), kennel" (14c.), perhaps from Italian nicchia "niche, nook," which is said to be from nicchio "seashell," itself said by Klein, Barnhart, etc. to be probably from Latin mitulus "mussel," but the change of -m- to -n- is not explained (Century Dictionary compares napkin from Latin mappa). Watkins suggests that the word is from an Old French noun derived from nichier "to nestle, nest, build a nest," via Gallo-Roman *nidicare from Latin nidus "nest" (see nidus), but that, too, has difficulties. The figurative sense is recorded by 1725. Biological use dates from 1927.