sadism (n.)

"love of cruelty," especially as evidence of a subconscious lust that the cruelty satisfies, 1888, from French sadisme, from the name of Count Donatien A.F. de Sade (1740-1815). Not a marquis, though usually now called one, he was notorious for the cruel sexual practices described in his novels.

The family name de Sade is toponymic, from the village now known as Saze in southern France. The village name is of uncertain etymology; one view puts it to be ultimately derived from Latin salix, "willow" while another considers it derived from the Visigothic personal name Sado.