half-turn

The compound noun 'half-turn' is a transparent combination of two native English elements. 'Half' descends from the Proto-Germanic halbaz, carrying the core sense of a division into two parts. 'Turn' entered Old English via Latin and ultimately derives from the Greek 'tornos', a tool for drawing circles, which metaphorically extended to mean any rotational movement. The literal compounding of these roots—'half' (one of two equal parts) and 'turn' (a rotation)—creates a precise geometric term denoting a 180-degree rotation, perfectly illustrating how English builds specific technical vocabulary from fundamental, concrete concepts.

Structure: half (partial) + turn (rotate) half: From Old English 'healf', meaning "side, part", of Germanic origin; related to Dutch 'half' and German 'halb'. Functions as a quantifier meaning one of two equal parts. turn: From Old English 'turnian', 'tyrnan', meaning "to rotate", from Latin 'tornare', from 'tornus' (lathe), from Greek 'tornos' (lathe, circle). Functions as a noun denoting an act of rotation.