[behind time] {adv.}
or {adj. phr.}
1a. Behind the correct time; slow.
* /That clock is behind time./
1b. Behind schedule; late.
* /The train is running behind time today./
2. Not keeping up; not at the proper time; overdue.
* /Your lessons are good, but why are you behind time?/* /We are behind time in paying the rent./
Contrast: AHEAD OF TIME, IN TIME, ON TIME.