Acidic

Antonyms of acidic:
alkalic, alkaline, amphiprotic, amphoteric, base-forming, saltlike, alcalescent, alkalescent, sweet, basic, bland, smooth, flat, flavorless, insipid, savorless, tasteless, zestless, dilute, thin, watery, weak, amusing, droll, merry, playful, sportive, waggish, gentle, mild, good-humored, good-natured, diplomatic, polite, suave, urbane, affable, cordial, genial, gracious, hospitable, sociable.