Old English borgian "to lend, be surety for," from Proto-Germanic *borg "pledge" (cognates: Old English borg "pledge, security, bail, debt," Old Norse borga "to become bail for, guarantee," Middle Dutch borghen "to protect, guarantee," Old High German boragen "to beware of," German borgen "to borrow; to lend"), from PIE root *bhergh- (1) "to hide, protect" (see bury). Sense shifted in Old English to "borrow," apparently on the notion of collateral deposited as security for something borrowed. Related: Borrowed; borrowing.