Entry 1 sense Webster, 1913 Acidification /əs-ĭdˌ-əf-ək-āsh'-ən/ · A·cid·i·fi·ca·tion · IPA /əˌsɪdɪfɪˈkeɪʃən/ 01 n. The act or process of acidifying, or changing into an acid. 1. The act or process of acidifying, or changing into an acid.