(1):

(adv.) When or that.

(2):

(adv.) From a definite past time until now; as, he went a month ago, and I have not seen him since.

(3):

(adv.) In the time past, counting backward from the present; before this or now; ago.

(4):

(conj.) Seeing that; because; considering; - formerly followed by that.

(5):

(prep.) From the time of; in or during the time subsequent to; subsequently to; after; - usually with a past event or time for the object.