"the domestic Bos taurus" (commonly meaning the castrated males, used to pull loads or for food), Middle English oxe, from Old English oxa "ox" (plural oxan), from Proto-Germanic *ukhson (source also of Old Norse oxi, Old Frisian oxa, Middle Dutch osse, Old Saxon, Old High German ohso, German Ochse, Gothic auhsa), from PIE *uks-en- "male animal," (source also of Welsh ych "ox," Middle Irish oss "stag," Sanskrit uksa, Avestan uxshan- "ox, bull"), said to be from root *uks- "to sprinkle," related to *ugw- "wet, moist." The animal word, then, is literally "besprinkler."
Also used from late Old English of the wild, undomesticated bovines. The black ox "misfortune, adversity, old age," etc., is by 1540s.
word-forming element making verbs (such as darken, weaken) from adjectives or nouns, from Old English -nian, from Proto-Germanic *-inojan (also source of Old Norse -na), from PIE adjectival suffix *-no-. Most active in Middle English and early modern English, hence most verbs in -en are comparatively recent.
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<a href="https://www.etymonline.com/word/oxen">Etymology of oxen by etymonline</a>
Harper, D. (n.d.). Etymology of oxen. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/oxen