'bestialize' originates from Late Latin and English formation: from the adjective 'bestial' (from Latin 'bestia' meaning 'beast') plus the verbalizing suffix '-ize' (from Late Latin '-izare' or Greek '-izein', meaning 'to make' or 'to do').

'bestialize' developed from the adjective 'bestial' (Middle English/Old French forms related to Latin 'bestia') with the addition of the productive verb-forming suffix '-ize', producing a verb meaning 'to make bestial' or 'to render beast-like'.

Initially the root sense was simply 'of or relating to beasts' (from 'bestial'); over time the verb form came to mean 'to render or treat as a beast', often with the connotation of brutalizing or degrading human dignity.