subaquatic

from WordNet (r) 3.0 (2006)

subaquatic
    adj 1: growing or remaining under water; "viewing subaqueous
           fauna from a glass-bottomed boat"; "submerged leaves"
           [syn: {subaqueous}, {subaquatic}, {submerged},
           {submersed}, {underwater}]
    2: partially aquatic; living or growing partly on land and
       partly in water; "a marginal subaquatic flora" [syn:
       {semiaquatic}, {subaquatic}]

from The Collaborative International Dictionary of English v.0.48

Subaquatic \Sub`a*quat"ic\, Subaqueous \Sub*a"que*ous\, a.
   1. Being under water, or beneath the surface of water;
      adapted for use under water; submarine; as, a subaqueous
      helmet.
      [1913 Webster]

   2. (Geol.) Formed in or under water; as, subaqueous deposits.
      [1913 Webster] Subarachnoid

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