insensate (ĭn-SĔN-sāt) Definition (Adjective) Wanting in mental or moral feeling; devoid of sensibility; unaffected, unmoved; unfeeling. (Of persons, or their qualities, actions, etc.) In Context "Beneath this polished exterior, one sensed, lived a man capable of insensate rage and unrestrained debauchery, a man who, even before arriving in the tropics, had cast off the ennobling bonds of civilization and honour." Alan Vanneman, Sherlock Holmes and the Giant Rat of Sumatra, 2002.