Meaning

noun the act of changing or reversing the direction of the course

noun act of changing in practice or custom

noun a shaving created when something is produced by turning it on a lathe

originFrom Middle English turninge, turnynge, turninde, turnand, turnende, from Old English tyrnende, turniende, present participle of Old English tyrnan, turnian (“to turn”). Equivalent to turn + -ing.

Etymology from Wiktionary, CC BY-SA 3.0