'Sometime back' or 'Sometimes back'?

Question

How should I decide between "sometime back" and "sometimes back"?

Sometime back I received a call from Mr. X

Sometimes back I received a call from Mr. X

Which sentence is correct?

Answer 1

'Sometime' refers to a single instance, which fits with the single telephone call.

'Sometimes' refers to a number of instances, in which case you would need to refer to more than one call, but you wouldn't use 'sometimes back'.

You have a typo and a missing article. The 1st phrase should be 'Sometime back I received a call from Mr X'.

You can also use 'A while ago' - 'One day/night'.

Answer 2

For your example the best choice would be

Some time ago I received a call from Mr.X.

Sometime refers to a moment of time, not a period, so saying sometime back is equivalent to something like Last year back or On my birthday back. Back is more correctly used with when or in:

• Back in 90's we would never think about that.
• Back when we didn't know each other, ...
• Back in the day, ... (this one is more idiomatic, meaning at a previous time with some other circumstances)

Sometime can be correctly used to express some important (for the 1st self) things that happened or will happen.

• He will be coming sometime between 6 and 9.
• The bank was robbed sometime last week.

It can also be used as an adjective meaning happening previously, but not now:

• The sometime renowned director is now asking for a new job.

And finally, always remember that there are three different versions:

• Sometimes = occasionally, from time to time
• Sometime = at a certain time, or moment
• Some time = a period of time, a while