(1):

(adv.) As if under the influence of the moon; in the manner of a lunatic.

(2):

(adv.) Once a month; in every month; as, the moon changes monthly.

(3):

(a.) Done, happening, payable, published, etc., once a month, or every month; as, a monthly visit; monthly charges; a monthly installment; a monthly magazine.

(4):

(a.) Continued a month, or a performed in a month; as, the monthly revolution of the moon.

(5):

(n.) A publication which appears regularly once a month.