a‧go S1 W1 /əˈɡəʊ $ əˈɡoʊ/
adverb[
Date: 1400-1500;
Origin: From the past participle of ago 'to pass away' (11-17 centuries), from Old English agan, from gan 'to go']
used to show how far back in the past something happened
5 minutes/an hour/20 years etc ago
Her husband died 14 years ago.long ago/a long time ago He should have finished at university long ago, but he kept taking extra courses.a minute/moment ago The little girl you saw a moment ago was my niece.a little/short while ago Tom got a letter from him just a little while ago. They moved to a new house some time ago (=a fairly long time ago). We had our bicentenary celebrations not that long ago.
GRAMMARago, before, previously Use
ago to say how much time has passed from the time something happened to the present time:
We went to Madrid two years ago.Use
before to say how much time passed from the time something happened to a time in the past:
Her husband had died many years before.Previously is used in the same way, but is more formal:
The meeting was a follow-up to one that had been held four days previously.► Use the past tense, not the present perfect, with
ago:
I started (NOT I've started) a new job a few weeks ago.► Do not use a preposition ('at', 'in', 'on' etc) before a phrase with
ago:
They first met fifteen years ago (NOT at/in fifteen years ago).► Do not use 'since' or 'before' with
ago:
I came to the US two months ago (NOT since/before two months ago). [TahlilGaran] Dictionary of Contemporary English ▲
agoadverb1. 
BAD: The accident happened at ten years ago.
GOOD: The accident happened ten years ago.
BAD: I came to England in two years ago.
GOOD: I came to England two years ago.
BAD: He went to Sydney before five years ago.
GOOD: He went to Sydney five years ago.
BAD: I started learning English since two years ago.
GOOD: I started learning English two years ago.
2. BAD: I'm writing in reply to your letter that I've received two days ago.
GOOD: I'm writing in reply to your letter that I received two days ago.
Usage Note:With references to past time such as
yesterday, last week, a year ago , use a past tense (NOT the present perfect): 'I came to England exactly six months ago.' (NOT 'have come')
3. BAD: The train left at exactly 3 o'clock. Just five minutes ago I had been stuck in a traffic jam.
GOOD: The train left at exactly 3 o'clock. Just five minutes before I had been stuck in a traffic jam.
Usage Note:See note at BEFORE 1 (
before)
[TahlilGaran] Dictionary of Common Errors ▲