Groin (?), n. [F. groin, fr. grogner to grunt, L. grunnire.] The snout of a swine. [Obs.] Chaucer.
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Groin, n. [Icel. grein distinction, division, branch; akin to Sw. gren, branch, space between the legs, Icel. greina to distinguish, divide, Sw. grena to branch, straddle. Cf. Grain a branch.] 1. (Anat.) The line between the lower part of the abdomen and the thigh, or the region of this line; the inguen.
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2. (Arch.) The projecting solid angle formed by the meeting of two vaults, growing more obtuse as it approaches the summit.
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3. (Math.) The surface formed by two such vaults.
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4. A frame of woodwork across a beach to accumulate and retain shingle. [Eng.] Weale.
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