A source of illumination.

(chiefly software) Whose constituent makeup, or source code, is not made publicly available.

(physics, meteorology) An extensive area of the Earth's surface over which bodies of air frequently remain for a sufficient time to acquire characteristic temperature and moisture properties imparted by that surface. Air so modified becomes identifiable as a distinct air mass. See airmass.

(scholarly studies) A written commentary which discusses previously produced original work of another author, especially a notable author.

(scholarly studies) An original work, especially one by a notable author whose work is now the subject of commentaries (secondary sources).

(sciences) a source of pollution, radiation, waves, fluid or other substance that has one specific location (and negligible physical extent, distinguishing a point source from other source geometries). In simulations they can often be approximated using mathematical point sources.

plural of source code

(astronomy) Any astronomical object that emits radio waves.

(software, slang, derogatory) open source computer software that is buggy, unstable, or lacking features.

Within a conceptual metaphor, the conceptual domain from which metaphorical expressions are drawn.