1. back up, support

give moral or psychological support, aid, or courage to

Example Sentences:
'She supported him during the illness'
'Her children always backed her up'

• support

2. back down, back off, back up

move backwards from a certain position

Example Sentences:
'The bully had to back down'

• back down
• back off

3. back, back up

establish as valid or genuine

Example Sentences:
'Can you back up your claims?'

• back

4. back up

make a copy of (a computer file) especially for storage in another place as a security copy

Example Sentences:
'You'd better back up these files!'

5. back up, choke, choke off, clog, clog up, congest, foul

become or cause to become obstructed

Example Sentences:
'The leaves clog our drains in the Fall'
'The water pipe is backed up'

• choke
• choke off
• clog
• clog up
• congest
• foul