名詞 back-up:

1. an accumulation caused by clogging or a stoppage
   同義詞：backup
2. someone who takes the place of another (as when things get dangerous or difficult)
   同義詞：stand-in, substitute, relief, reliever, backup, backup man, fill-in
3. a subordinate musical part; provides background for more important parts
   同義詞：accompaniment, musical accompaniment, backup, support
4. (computer science) a copy of a file or directory on a separate storage device
   同義詞：backup, computer backup
5. the act of providing approval and support
   同義詞：backing, backup, championship, patronage

動詞 back-up:

1. give moral or psychological support, aid, or courage to
   同義詞：support, back up
2. move backwards from a certain position
   同義詞：back up, back off, back down
3. establish as valid or genuine
   同義詞：back, back up
4. make a copy of (a computer file) especially for storage in another place as a security copy
   同義詞：back up
5. become or cause to become obstructed
   同義詞：clog, choke off, clog up, back up, congest, choke, foul

1. The police had military back-up.
   警方有軍隊作後盾。