any of a class of drugs used to control heartbeat, relieve angina pectoris, treat hypertension, etc. by blocking the nerve impulses that normally excite the beta receptors
See beta blocker in American Heritage Dictionary 4
noun
A drug, such as propanolol, that opposes the excitatory effects of norepinephrine released from sympathetic nerve endings at beta-receptors and is used for the treatment of angina, hypertension, arrhythmia, and migraine. Also called beta-adrenergic blocking agent.