Tim Bowen refuses to back down over this set of phrasal verbs.
‘The dispute is now in its third week and neither side seems prepared to back down.’ If you back down, you stop asking for something or saying that you will do something, usually because a lot of people oppose your position.
To back off is to move backwards in order to get further away from something, as in ‘They asked the crowd to back off to let the emergency services through’. If you ask someone to back off, you are asking them to stop criticizing you or stop telling you what to do, as in ‘Back off, will you? I’ll do it when I’m ready to do it’.
A building or garden that backs onto a place has that place directly behind it, as in ‘It’s a nice house but, unfortunately, it backs onto the main railway line’.
To back out is to decide not to do something you had previously agreed to do, as in ‘I said I would support the venture and I’m not backing out at this late stage’. Pull out can be used with the same meaning.
Back up has several meanings. Perhaps the best-known is its use to mean to copy computer information as most computer users will be familiar with the on-screen warning ‘You have not backed up your files’. It can also mean to give support to someone by saying that you agree with them, as in ‘If I ask for more money, will you back me up?’ A similar meaning is that of supporting or corroborating evidence or an explanation, as in ‘It’s an interesting theory but do you have the evidence to back it up?’