(a) quarter of (a given hour in time)

A quarter of an hour (15 minutes) before a particular hour. The phrase "(a) quarter of" can be used by itself or followed by a specific hour (e.g., "quarter of six," which means 5:45). Primarily heard in US. A: "What time does the movie start?" B: "Not until a quarter of eight, so we've got plenty of time!" I thought I'd be home already, but with this traffic, it'll be quarter of before I'm back. After lunch, the kids get to have recess until quarter of one.