back up
— phrasal verb with back uk/bæk/us/bæk/verb
If traffic backs up, the vehicles have to wait in a long line because there are too many of them:
The traffic is starting to back up on the M25.
Thesaurus: synonyms and related words
On the road: traffic jams
- back
- backed up
- bottleneck
- bumper
- bumper to bumper idiom
- congested
- gridlock
- jam
- rasta roko
- rush hour
- snarled up
- sock
- sock sth/sb in (with sb)
- tail
- tail back
- tailback
- traffic
- traffic calming
- traffic jam