WordNet (r) 3.0 (2006):

beta receptor
    n 1: receptors postulated to exist on nerve cell membranes of
         the sympathetic nervous system in order to explain the
         specificity of certain agents that affect only some
         sympathetic activities (such as vasodilation and increased
         heart beat) [syn: beta receptor, beta-adrenergic
         receptor, beta-adrenoceptor]