1 (wiktionary) 2 (zh.wikipedia) 3 (en.wikipedia) 4 (glosbe)

Compounds Expand your vocabulary by studying more complex words built by the 'core words'.

backup C1 n.

HSK 3.0 (2022)	Big5	Gb	Pin	Eng
7	備用	备用	bèiyòng	reserve, spare, alternate, backup
7	後備	后备	hòubèi	reserve, backup