N-VAR
(物资、人员等的)支持,辅助
Backup consists of extra equipment, resources, or people that you can get help or support from if necessary.
例句
There is no emergency back-up immediately available...
手头无法获得应急支持。
Alternative treatments can provide a useful back-up to conventional treatment.
替代疗法能为传统的治疗提供有效的辅助。