The Collaborative International Dictionary of English v.0.48:

Knag \Knag\ (n[a^]g), n. [Cf. Prov. G. knagge a knot in wood,
   Sw. knagg, Dan. knag a hook to hand clothes on, a bracket;
   Gael. & Ir. cnag peg, knob.]
   1. A knot in wood; a protuberance. --Wright.
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   2. A wooden peg for hanging things on. --Wright.
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   3. The prong of an antler. --Holland.
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   4. The rugged top of a hill. [Prov. Eng.] --Halliwell.
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