Definitions for sadismˈseɪ dɪz əm, ˈsæd ɪz-
Random House Webster's College Dictionary
sa•dismˈseɪ dɪz əm, ˈsæd ɪz-(n.)
sexual gratification gained by causing pain or degradation to others.
pleasure in being cruel.
Origin of sadism:
1885–90; < F sadisme; see Sade , -ism
sexual pleasure obtained by inflicting harm (physical or psychological) on others
the enjoyment of inflicting pain without pity
achievement of sexual gratification by inflicting pain on others
gaining sexual excitement and satisfaction by watching pain inflicted by others on their victims
a morbid form of enjoyment achieved by acting cruelly to another, or others
(in general use) Deliberate cruelty, either mental or physical; also refers to cruelty inflicted upon animals, regardless of gratification
Origin: Named after the Marquis de Sade, famed for his libertine writings depicting the pleasure of inflicting pain to others. The word for "sadism" (sadisme) is forged or acknowledged in the 1834 posthumous reprint of French lexicographer Boiste's Dictionnaire universel de la langue française; it is reused along with "sadist" (sadique) in 1862 by French critic Sainte-Beuve in his commentary of Flaubert's novel Salammbô; it is reused (possibly independently) in 1886 by Austrian psychiatrist Krafft-Ebing in Psychopathia Sexualis which popularized it; it is directly reused in 1905 by Freud in Three Essays on the Theory of Sexuality which definitely established the word.
U.S. National Library of Medicine
A condition in which there is a derivation of pleasure from inflicting pain, discomfort or humiliation on another person or persons. The sexual significance of sadistic wishes or behavior may be conscious or unconscious.