c. 1200, cruelte, "indifference to, or pleasure taken in, the distress or suffering of any sentient being," from Old French crualté (12c., Modern French cruauté), from Latin crudelitatem (nominative crudelitas) "cruelty," from crudelis "rude, unfeeling; cruel, hard-hearted," related to crudus "rough, raw, bloody" (see crude). Meaning "a cruel act" is from late 14c.
"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.
"a grip, grasp, tight hold," c. 1200, plural, cleches, from or related to the verb clucchen, clicchen (see clutch (v.)). Clutches "the hands," suggesting grasping rapacity or cruelty, is from 1520s.
1530s, "enormous wickedness," from French atrocité or directly from Latin atrocitatem (nominative atrocitas) "cruelty, fierceness, harshness," noun of quality from atrox "fierce, cruel, frightful," from PIE *atro-ek-, from root *ater- "fire" + root *okw- "to see;" thus "of fiery or threatening appearance." The meaning "an atrocious deed" is from 1793.
"barbarous cruelty," late 15c., from French inhumanité (14c.) or directly from Latin inhumanitatem (nominative inhumanitas) "inhuman conduct, savageness; incivility, rudeness," noun of quality from inhumanus "inhuman, savage, cruel" (see inhuman).
And Man, whose heav'n-erected face
The smiles of love adorn,—
Man's inhumanity to man
Makes countless thousands mourn!
[Robert Burns, "Man was Made to Mourn," 1784]