Function: intransitive verb
Date: 1837
: to accumulate in a congested state <traffic backed up for miles>
transitive verb
1 : to move into a position behind (a teammate) in order to assist on a play
2 : HOLD BACK 1
3 : to make a copy of (a computer file or data) to protect against accidental loss also : to make copies of all the files on (a hard drive)