The Collaborative International Dictionary of English v.0.48:

Groin \Groin\, v. t. [imp. & p. p. Groined (groind); p. pr. &
   vb. n. Groining.] (Arch.)
   To fashion into groins; to build with groins.
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         The hand that rounded Peter's dome,
         And groined the aisles of Christian Rome,
         Wrought in a sad sincerity.              --Emerson.
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The Collaborative International Dictionary of English v.0.48:

Groined \Groined\, a. (Arch.)
   Built with groins; as, a groined ceiling; a groined vault.
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