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pin (n.)

Old form(s): pinne

[archery] peg in the middle of a target; centre

LLL IV.i.137	[Costard to Boyet, of Maria] Then will she get the upshoot by cleaving the pin [with bawdy pun]
RJ II.iv.15	[Mercutio to Benvolio, of Romeo] the very pin of his heart cleft with the blind bow-boy's butt-shaft