Origin and history of knap

mid-14c., "a deception, trick, device," a word of uncertain origin. Perhaps from or related to a Low German word meaning "a sharp sounding blow" (compare Middle English knak, late 14c.; German knacken "to crack;" also knap) and of imitative origin. Sense of "special skill" (in some specified activity) is first recorded 1580s, if this is in fact the same word. In old slang (mid-18c. to mid-19c.) nacky meant "full of knacks; ingenious, dexterous." For pronunciation, see kn-.

Middle English spelling of a common Germanic consonant-cluster (in Old English it was graphed as cn-; see K). The sound it represented persists in most of the sister languages, but in English it was reduced to "n-" in standard pronunciation by 1750, after about a century of weakening and fading. It was fully voiced in Old and Middle English.