Webster's Revised Unabridged Dictionary · 1913

Knap

Knap (nap) , noun

[Anglo-Saxon cnap, cnapp, top, knob, button; compare Icelandic knappr knob, Swedish knapp, Danish knap button, Welsh, Gael., & Ir. cnap knob, button, and English knop.]

A protuberance; a swelling; a knob; a button; hence, rising ground; a summit. See Knob, and Knop.
The highest part and knap of the same island. — Holland

Knap , transitive verb

[Dutch knappen to chew, bite, crack, take hold of; prob. of imitative origin.]

1.
To bite; to bite off; to break short. [Obsolete or Provincial English]
He will knap the spears apieces with his teeth. — Dr. H. More
He breaketh the bow, and knappeth the spear in sunder. — Bible (KJV) - Psalm xlvi. 9 (Book of Common Prayer.)
2.
To strike smartly; to rap; to snap. [Chiefly British] — Bacon

Knap , intransitive verb

To make a sound of snapping. — Wiseman

Knap , noun

A sharp blow or slap. — Halliwell