"characteristic of a sadist," 1892, after German sadistisch; see sadism. Related: Sadistically. For "of or characteristic of de Sade or his writings or philosophy," Sadean has been used.
Entries linking to sadistic
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.