Media, Publishing, Typography The punctuation mark ⟨,⟩ used to indicate a set of parts of a sentence or between elements of a list.
No points were used by the ancient printers, excepting the colon and the period; but, after some time, a short oblique stroke, called a virgil, was introduced, which answered to the modern comma. In the fifteenth century this punctuation was improved by the famous Aldus Manutius with the typographical art in general; when he gave a better shape to the comma, added the semicolon, and assigned to the former points more proper places.1828, Richard Thomson, Illustrations of the History of Great Britain, Vol. II, pp. 145–6
Biology, Entomology, Natural sciences Any of various nymphalid butterflies of the genus Polygonia, having a comma-shaped white mark on the underwings, especially Polygonia c-album and Polygonia c-aureum of North Africa, Europe, and Asia.
Commas (Polygonia comma) and Question Marks (Polygonia interrogationis) occur from the Gulf Coast to Canada and west to the Rockies. [...] Question Marks and Commas are handsome butterflies with burnt orange and black markings. [...] On the underside of each hind wing of the Comma is a small, distinctive silver hook that resembles a comma.2004, Scott Shalaway, “Close-ups”, in Butterflies in the Backyard, Mechanicsburg, Pa.: Stackpole Books, →ISBN, page 18:
Other members of this genus that are frequently encountered in the park are the eastern comma (P. comma) and question mark (P. interrogationis).2013, Ann Simpson, Rob Simpson, “Butterflies and Moths”, in Nature Guide to Shenandoah National Park (Falcon Pocket Guide), Guilford, Conn.; Helena, Mont.: Falcon Guides, Globe Pequot Press, →ISBN, page 91:
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Entertainment, Lifestyle, Music A difference in the calculation of nearly identical intervals by different ways.
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Biology, Genetics, Medicine, Natural sciences, Sciences A delimiting marker between items in a genetic sequence.
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Rhetoric In Ancient Greek rhetoric, a short clause, something less than a colon, originally denoted by comma marks. In antiquity it was defined as a combination of words having no more than eight syllables in all. It was later applied to longer phrases, e.g. the Johannine comma.