standby

Từ điển WordNet v3.1 - WordNet Dictionary

I - noun

1. something that can be relied on when needed (Freq. 1)
• Derivationally related forms:
stand by
• Hypernyms:
thing
2. an actor able to replace a regular performer when required
• Syn:
understudy
• Derivationally related forms:
stand by, understudy (for: understudy)
• Hypernyms:
actor, histrion, player, thespian, role player

II - adjective

ready for emergency use
- a standby generator
- a standby crew
• Similar to:
secondary