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1610s, "shallow recess in a wall," from French niche "recess (for a dog), kennel" (14c.), perhaps from Italian nicchia "niche, nook," from nicchio "seashell," said by Klein and Barnhart to be probably from Latin mitulus "mussel," but the change of -m- to -n- is not explained. Watkins suggests that the word is from an Old French noun derived from nichier "to nestle, nest, build a nest," via Gallo-Romance *nidicare from Latin nidus "nest;" but that has difficulties, too. Figurative sense is first recorded 1725. Biological use dates from 1927.
niche (nĭch, nēsh)
An eroded or ulcerated area detected by contrast radiography.
The function or position of an organism or a population within an ecological community.
The particular area within a habitat occupied by an organism.
The function or position of a species within an ecological community. A species's niche includes the physical environment to which it has become adapted as well as its role as producer and consumer of food resources. See also competitive exclusion principle.