knock off (4) Informal
Meaning: to reduce something, like a price or an amount
- knock off sth I'll bargain with her and see if she'll knock off a few dollars for us.
- knock sth off They've already knocked ten percent off the usual price, so they probably won't knock any more off.
Mark has knocked two seconds off his previous best time of 4 minutes and 20 seconds. His best time is now