'ferox' originates from Latin, specifically the word 'ferox', where the element 'fer-' is related to 'ferus' meaning 'wild' and the suffix (as in formations) conveyed being 'full of' or 'inclined to' the quality.

'ferox' was used in Classical Latin with the meaning 'fierce, wild'; it continued in Medieval and Renaissance Latin and was later borrowed unchanged into English in learned, literary, and scientific (especially taxonomic) contexts.

Initially it meant 'wild, fierce' in Latin; over time the core meaning has remained largely the same, though in English use it became specialized (literary, archaic, or technical in taxonomy) rather than common everyday vocabulary.