Definitions
American Heritage® Dictionary of the English Language, Fourth Edition
- adv. Gone by; past: two years ago.
- adv. In the past: It happened ages ago.
Century Dictionary and Cyclopedia
- Gone; gone by; gone away; past; passed away: always after the noun.
- In past time; in time gone by: only in the phrase long ago.
Wiktionary
- adj. Gone; gone by; gone away; passed; passed away.
- adj. Nearly gone; dead (used in Devonshire at the turn of the 19th century)
- prep. Past; gone by; since.
GNU Webster's 1913
- Past; gone by; since.
WordNet 3.0
- adj. gone by; or in the past
- adv. in the past
Etymologies
- Middle English, past participle of agon, to go away, from Old English āgān : ā-, intensive pref. + gān, to go; see ghē- in Indo-European roots.
Examples
“A week ago (A little more cheese, waiter) a week ago I grieved for the dying summer.”
“A short time ago -- (this _not long ago_ is with us men -- centuries) -- my rays followed a young artist; it was in the realm of the Pope, in the city of the world, in Rome.”
“Everything is saved, that is something the church is closed not too long ago, 66 years ago» Enthusiasts of the Society for the Study of Russian manor in the record books and photographs, as destroyed the last nest of the old Russia, carrying tourists and - shrug.”
“TeamBrian 11 points 20 hours ago TeamBrian 11 points 20 hours ago moskaudancer 5 points 17 hours ago moskaudancer 5 points 17 hours ago NSMike 1 point 11 hours ago*”
“An_Anteater 7 points 52 minutes ago matt2500 2 points 1 hour ago* matt2500 2 points 1 hour ago* deaathleopards 1 point 16 minutes ago you'll need to login or register to do that is it really that easy? only one way to find out ...”
“When I first read that, I thought "roomba" was new coolspeak for a "roommate", and that I was falling behind the times. switchmotiv 6 points 7 hours ago switchmotiv 6 points 7 hours ago saskpirate420 4 points 7 hours ago saskpirate420 4 points 7 hours ago TheEllimist 1 point 2 minutes ago kermityfrog 3 points 6 hours ago kermityfrog 3 points 6 hours ago HenkPoley 1 point 1 hour ago*”
“For example, why does hiding a code snippet take so long? smokestack 1 point 19 minutes ago smokestack 1 point 19 minutes ago smokestack 2 points 2 hours ago smokestack 2 points 2 hours ago smokestack 1 point 56 minutes ago smokestack 1 point 56 minutes ago turiya04 1 point 4 hours ago* turiya04 1 point 4 hours ago*”
“Paczesiowa 12 points 3 hours ago vagif 1 point 12 minutes ago* vagif 1 point 12 minutes ago*”
“On the other hand, someone taking 911 calls is sloetjes 24 points 59 minutes ago sloetjes 24 points 59 minutes ago RoboBama 7 points 1 hour ago*”
“LeeJunFan 2 points 36 minutes ago LeeJunFan 2 points 36 minutes ago nightowl_777 13 points 12 hours ago nightowl_777 13 points 12 hours ago dfranke 4 points 7 hours ago* dfranke 4 points 7 hours ago*”

qroqqa Problem of classification: preposition or adverb? A construction like 'three weeks ago' is similar to 'three weeks later', where 'later' is the head adverb and 'three weeks' is a premodifier. However, in all such unequivocally adverbial senses, the modifier is optional. Since 'ago' can't be used on its own, the CGEL takes it to be a preposition and the NP 'three weeks' to be its preposed complement. Jul 7, 2009