savageness (n.)

c. 1400, savagenes, "state of being uncivilized," in Modern English also "uncivilized character or condition;" see savage (adj.) + -ness.

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truculence (n.)
1727, from Latin truculentia "savageness, cruelty," from truculentus (see truculent). Related: Truculency (1560s).
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inhumanity (n.)

"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]
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