Source : Webster's Revised Unabridged Dictionary (1913)

Spa \Spa\ (?; 277), n.
   A spring or mineral water; -- so called from a place of this
   name in Belgium.

Source : WordNet®

spa
     n 1: a health resort near a spring or at the seaside [syn: {watering
          place}, {watering hole}]
     2: a fashionable hotel usually in a resort area [syn: {resort
        hotel}]
     3: a place of business with equipment and facilities for
        exercising and improving physical fitness [syn: {health
        spa}, {health club}]