urticaria(n = noun.state) hives, nettle rash, urtication - 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;
is a kind of efflorescence, rash, roseola, skin rash, hypersensitivity reaction

   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. [1913 Webster]

urticaria, n. Med. nettle-rash.

Etymology:
mod.L f. L urtica nettle f. urere burn