Acidification is the correct term to refer to something becoming more acidic (or "less basic" if you prefer). It doesn't mean that something has a pH below 7.

Acidification is the correct term to refer to something becoming more acidic (or "less basic" if you prefer). It doesn't mean that something has a pH below 7. pH is directly related to the concentration of H+ ions in solution, which is equivalent to being inversely correlated with the concentration of OH- ions in solution (a reduction in OH- ion concentration means a relative increase in H+ ion concentration).