The Collaborative International Dictionary of English v.0.48:

Integument \In*teg"u*ment\, n. [L. integumentum, fr. integere to
   cover; pref. in- in, on + tegere to cover: cf. F.
   int['e]gument. See 1st n-, and Tegument.]
   That which naturally invests or covers another thing, as the
   testa or the tegmen of a seed; specifically (Anat.), a
   covering which invests the body, as the skin, or a membrane
   that invests a particular part.
   [1913 Webster]

WordNet (r) 3.0 (2006):

integument
    n 1: an outer protective covering such as the skin of an animal
         or a cuticle or seed coat or rind or shell