In nautical terms, to tilt or turn a ship's yard or gun upward at an angle; the angle at which such equipment is positioned.
From 'cock' (to tilt up, like a rooster's comb) plus 'bill' (a pointed projection or nautical equipment). Maritime terminology from the Age of Sail, referring to the positioning of yards and artillery.
This is wonderful—sailors borrowed 'cock' (the verb meaning to tilt upward) and applied it to ship equipment, creating 'cockbill' as technical jargon. It shows how 'cock' as a verb (meaning to stick up) was different from 'cock' as a noun (a rooster)!
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