The Collaborative International Dictionary of English v.0.48:

Cement \Ce*ment"\ (s[e^]*m[e^]nt" or s[e^]m"[e^]nt), n. [OF.
   cement, ciment, F. ciment, fr. L. caementum a rough, unhewn
   stone, pieces or chips of marble, from which mortar was made,
   contr. fr. caedimentum, fr. caedere to cut, prob. akin to
   scindere to cleave, and to E. shed, v. t.]
   1. Any substance used for making bodies adhere to each other,
      as mortar, glue, etc.
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   2. A kind of calcined limestone, or a calcined mixture of
      clay and lime, for making mortar which will harden under
      water.
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   3. The powder used in cementation. See Cementation, n., 2.
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   4. Bond of union; that which unites firmly, as persons in
      friendship, or men in society. "The cement of our love."
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   5. (Anat.) The layer of bone investing the root and neck of a
      tooth; -- called also cementum.
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   Hydraulic cement. See under Hydraulic.
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WordNet (r) 3.0 (2006):

cementum
    n 1: a specialized bony substance covering the root of a tooth
         [syn: cementum, cement]