(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).

A source of power such as a generator or mains outlet.

plural of power source

A measured amount of radioisotope sealed within a protective container.

Alternative spelling of closed-source

A source from which useful energy can be extracted or recovered either directly or by means of a conversion or transformation process (e.g. solid fuels, liquid fuels, solar energy, biomass, etc.)

(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.