How to say "backup" in Japanese

• 控えひかえCommon
  nounCovers 'backup' as a spare or reserve kept on hand in case something happens to the original. A typical use is a spare copy of an important document.
• サブCommon
  nounCovers 'backup' as a substitute or secondary option — something that takes over when the main one is unavailable. A typical use is a second device kept as a stand-in.
• 退避たいひCommon
  noun, suru verb, intransitive verbCovers the data sense of 'backup': backing up data, as in computing. Use it when 'backup' refers to data itself, not to a spare or a substitute.

Choose 退避 for backing up data, 「控え」 for a spare or reserve kept on hand, and 「サブ」 when 'backup' means a substitute or secondary option that stands in.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 控えひかえreserve
• サブsub
• 下支えしたざさえsupport
• 助太刀すけだちassistance (in a fight)
• バックアップbackup
• 退避たいひbackup (of data)