What is the origin of ineluctable?

Ineluctable “incapable of being evaded” derives from Latin inēluctābilis, equivalent to the prefix in- “not” and the verb ēluctārī “to force a way out or over, surmount.” The latter is a compound of ē-, the prefix version of ex “out of, from,” and the verb luctārī “to struggle, wrestle.” Another English derivative of luctārī is the noun reluctance, which literally means “the state of struggling against,” and if you’re a fan of wrestling, you may have already connected Spanish lucha—as in the phrase lucha libre (literally “free wrestling”)—to luctārī. The evolution of Latin luctārī to Spanish lucha demonstrates a common sound correspondence, namely, that Latin -ct- often (though not always) becomes -ch- in Spanish. Also compare Latin nox (stem noct-) with Spanish noche “night,” Latin octõ with Spanish ocho “eight,” and Latin ​​prōfectus with Spanish provecho “profit.” Ineluctable was first recorded in English circa 1620.