Ago (adverb)

1. Before the present time; in the past.
2. Earlier in time; previously.

Origin:

Middle english: from old english ongeán "opposite, against" + gōn "gone", from gān "go".

Examples:

1. I did it an hour ago.
2. I saw him yesterday ago.
3. I met her a week ago.
4. I went there a month ago.
5. I did it a year ago.