From The Collaborative International Dictionary of English v.0.48:
Cop \Cop\ (k[o^]p), n. [AS. cop; cf. G. kopf head. Cf. Cup,
Cob.]
1. The top of a thing; the head; a crest. [Obs.]
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Cop they used to call
The tops of many hills. --Drayton.
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2. A conical or conical-ended mass of coiled thread, yarn, or
roving, wound upon a spindle, etc.
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3. A tube or quill upon which silk is wound.
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4. (Mil. Arch.) Same as Merlon.
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5. A policeman. [Slang]
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Cop waste, a kind of cotton waste, composed chiefly of
remnants of cops from which the greater part of the yarn
has been unwound.
[1913 Webster] copacetic