the.com/epithet

means A descriptive word or phrase attached to a person's name — sometimes a formal title of honor, sometimes just a cutting insult — that sums them up in a word or two.

from From Greek 'epitheton,' meaning 'something added' — built from 'epi-' (upon, in addition) plus 'tithenai' (to place, to put). So an epithet is literally a word 'placed upon' a name. The Greeks used it for descriptive tags like 'swift-footed Achilles,' but the same machinery that builds praise builds insult — which is how the word drifted toward its modern, sharper sense of a hurled slur, even as its older, grander meaning (a title earned, like 'the Great') never left.