Definitions:

1. Acting in a savage, inhuman, or violent way. NOUN
   • She could not the beastliness with which he treated the animals.
2. Can describe something nasty, filthy, or offensive physically or morally. NOUN
   • There was a certain beastliness in the way he manipulated others for pleasure.
3. Extremely unpleasant or disgusting nature. NOUN
   • He complained about the beastliness of the weather.
4. Vicious, cruel, or brutal behavior. NOUN
   • The beastliness of the attack shocked everyone.

Synonyms:

• brutality
• cruelty
• depravity
• meanness
• nastiness
• vileness