impermeable

from WordNet (r) 3.0 (2006)

impermeable
    adj 1: preventing especially liquids to pass or diffuse through;
           "impermeable stone"; "an impermeable layer of scum"; "a
           coat impermeable to rain" [ant: {permeable}]

from The Collaborative International Dictionary of English v.0.48

Impermeable \Im*per"me*a*ble\, a. [Pref. im- not + permeable:
   cf. F. imperm['e]able, L. impermeabilis.]
   Not permeable; not permitting passage, as of a fluid. through
   its substance; impervious; impenetrable; as, India rubber is
   impermeable to water and to air. -- {Im*per"me*a*ble*ness},
   n. -- {Im*per"me*a*bly}, adv.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

46 Moby Thesaurus words for "impermeable":
      close, close-knit, close-textured, close-woven, closed, compact,
      compacted, compressed, concentrated, concrete, condensed,
      congested, consolidated, crammed, crammed full, crowded, dense,
      firm, gluey, hard, heavy, hermetic, holeproof, impassable,
      impenetrable, impervious, jam-packed, jammed, massive, nonporous,
      nonpuncturable, packed, punctureproof, sealed, serried, solid,
      substantial, thick, thick-growing, thickset, unpassable,
      unperforable, unpierceable, viscid, viscose, viscous

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