What does 'not since' mean? How should i use?

[svidrigaylov]

What does 'not since' mean? How should I use it?

 

[Rover_KE]

Click here and bookmark the site for future reference.

 

[teechar]

What does 'not since' mean?

It means something has not occurred or has not applied, starting from a particular time/date in the past until now.

How should I use it?

See the link provided by Rover_KE above.

For example,
A: Have there been any earthquakes in this area?
B: Not since March 2009. [ There haven't been any earthquakes in this area since March 2009.]