Meaning

noun a special way of doing something

originLate Middle English, use as "special skill" from 1580. Possibly from 14th century Middle English krak, knack (“a sharp sound or blow”), knakke, knakken, from Middle Low German and of imitative origin, similar to Dutch knak (“snap, crack”). Latter cognate to German knacken (“to crack”). See also crack.

Etymology from Wiktionary, CC BY-SA 3.0