Source : Webster's Revised Unabridged Dictionary (1913)

Urticaria \Ur`ti*ca"ri*a\, n. [NL. See {Urtica}.] (Med.)
   The nettle rash, a disease characterized by a transient
   eruption of red pimples and of wheals, accompanied with a
   burning or stinging sensation and with itching; uredo.

Source : WordNet®

urticaria
     n : an itchy skin eruption characterized by weals with pale
         interiors and well-defined red margins; usually the
         result of an allergic response to insect bites or food or
         drugs [syn: {urtication}, {hives}, {nettle rash}]