Noun

(en noun)

(architecture) A cavity, hollow, or recess, generally within the thickness of a wall, for a statue, bust, or other erect ornament. Hence, any similar position, literal or figurative.

"Images defended from the injuries of the weather by niches of stone wherein they are placed." --Evelyn.

(biology) A function within an ecological system to which an organism is especially suited.

(by extension) Any position of opportunity for which one is well-suited, such as a particular market in business.

An arrow woven into a Muslim prayer rug pointing in the direction of Mecca.

Noun

(en noun)

Subject; theme; a category or general area of interest.

*{{quote-magazine, date=2013-08-03, volume=408, issue=8847, magazine=(The Economist)

, title= The machine of a new soul , passage=The yawning gap in neuroscientists’ understanding of their topic is in the intermediate scale of the brain’s anatomy. Science has a passable knowledge of how individual nerve cells, known as neurons, work. It also knows which visible lobes and ganglia of the brain do what. But how the neurons are organised in these lobes and ganglia remains obscure. Yet this is the level of organisation that does the actual thinking—and is, presumably, the seat of consciousness.}}

(Internet) Discussion thread.

(obsolete) An argument or reason.

* Bishop Wilkins

contumacious persons, who are not to be fixed by any principles, whom no topics can work upon

(obsolete, medicine) An external local application or remedy, such as a plaster, a blister, etc.

(Wiseman)