Monopolar lead (syn.: unipolar lead, unipolar lead; lat. unipolaris single + gr. physiol. ópos, ópōn, ópus opposite, reverse) - in physiology, a medical procedure during which unilateral removal (abduction) of a part of the drug occurs or extraction it from the body. In dental practice, retraction is the removal of the mucous membrane from the socket of an extracted tooth.