(uncountable) Sonic barrier, the sudden increase in drag (resistance) and other effects experienced by moving objects when their speed approaches that of sound or becomes supersonic (which used to be considered a barrier to higher speeds).

(Christianity) An annual feast day celebrating the faithful departed on the second day of November, immediately following All Saints' Day. / (uncommon) Synonym of Tomb Sweeping Day, a Chinese holiday.

(molecular biology) A technique whereby biological molecules (especially DNA fragments) are separated by electrophoresis and then transferred from a gel to an immobilizing medium, under the influence of an electric field, for analysis.

(uncountable) The technical discipline of recording and producing sound. / (less frequently) Engineering which is sound in the sense of being reliable.

One who practices sound engineering.

The southern part of any region; alternative letter-case form of south. / The Global South. / (US) Those states which formed the Confederacy during the American Civil War.

(not in US) from or pertaining to the southern part of any region

A surname. / Ellipsis of Southern Comfort.

The strait that separates Zealand (an island of Denmark) from Scania (part of Sweden); also sometimes called by the Danish name, Øresund. / Synonym of Plymouth Sound, Devon, England.

Of, facing, situated in, or related to the south-west / (of a wind) blowing from the south-west; south-westerly