(1):

(v. t.) Not strict or stringent; not exact; loose; weak; vague; equivocal.

(2):

(v. t.) Not tense, firm, or rigid; loose; slack; as, a lax bandage; lax fiber.

(3):

(n.) A looseness; diarrhea.

(4):

(v. t.) Having a looseness of the bowels; diarrheal.