The word "vermin" entered English in the early 14th century from Anglo-French and Old French vermin, which itself derived from the Vulgar Latin verminum, a collective noun. This Latin term is a back-formation from the classical Latin vermis, meaning "worm." The semantic logic follows a path from the specific (worm) to a general collective category for various low, crawling, or parasitic creatures. Over time, its application broadened metaphorically to describe people perceived as similarly parasitic or destructive to the social order, solidifying its modern dual meaning encompassing both biological pests and despised individuals.

The word is a simplex loanword from French. It is not productively segmented into meaningful sub-parts in modern English spelling.