means the quality of being certain to happen no matter what anyone does to prevent it.

from From Latin inevitabilis, built from in- ("not") plus evitabilis ("avoidable"), which traces back to evitare, "to shun or avoid" — itself made of e- ("out") and vitare ("to shun"). So at its root the word literally means "that which cannot be shunned," no matter how nimbly you sidestep. It slipped into English through the related adjective inevitable in the 1400s, with the noun form following to name the thing itself: not just an event you can't dodge, but the whole condition of dodging being pointless.