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

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "integument":
   Leatherette, Leatheroid, border, circumference, coat, cortex,
   covering, crust, cuticle, dermis, envelope, epidermis, exterior,
   external, facade, face, facet, fell, fleece, flesh, fringe, front,
   fur, furring, hide, imitation fur, imitation leather, jacket,
   leather, leather paper, lineaments, outer face, outer layer,
   outer side, outer skin, outline, outside, pelt, peltry, periphery,
   rawhide, rind, sheath, shell, skin, skins, superficies,
   superstratum, surface, tegmen, tegmentum, tegument, top, vair