The Collaborative International Dictionary of English v.0.48:

Aqua \A"qua\, n. [L. See Ewer.]
   Water; -- a word much used in pharmacy and the old chemistry,
   in various signification, determined by the word or words
   annexed.
   [1913 Webster]

   Aqua ammoni[ae], the aqueous solution of ammonia; liquid
      ammonia; often called aqua ammonia.

   Aqua marine, or Aqua marina. Same as Aquamarine.

   Aqua regia. [L., royal water] (Chem.), a very corrosive
      fuming yellow liquid consisting of nitric and hydrochloric
      acids. It has the power of dissolving gold, the "royal"
      metal.

   Aqua Tofana, a fluid containing arsenic, and used for
      secret poisoning, made by an Italian woman named Tofana,
      in the middle of the 17th century, who is said to have
      poisoned more than 600 persons. --Francis.

   Aqua vit[ae][L., water of life. Cf. Eau de vie,
      Usquebaugh], a name given to brandy and some other
      ardent spirits. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

aqua
    n 1: a shade of blue tinged with green [syn: greenish blue,
         aqua, aquamarine, turquoise, cobalt blue, peacock
         blue]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

AQUA. Water. This word is used in composition, as aquae ductus, &c. 2. It is
a rule that water belongs to the land which it covers, when it is
stationary: aqua cedit solo. But the owner of running water, or of a water
course, cannot stop it the inferior inheritance having a right to the flow:
aqua currit et debet currere, ut currere solebat.