Defending a term such as prevenient grace poses the same problem as defending such terms as trinity, total depravity, supra-, infra-, or sublapsarianism, or even Bible, for such terms do not appear in the Bible.
What, then, does the Arminian mean by the term prevenient grace? The word prevenient means “preceding;” thus the term, in its most simple form, means “grace which goes before,” or, “preceding grace” (or, as in ancient usage, “preventing grace”). So when the Bible claims that people are “saved by grace” (Eph. 2:8), Arminians understand that this grace must precede salvation if a person is to be saved (something which no Calvinist would deny).