Groundswell

The standard polite response to thanks. Slightly more formal in feel than 'de nada' but used freely in everyday speech.

A spontaneous exclamation after being startled. 'Susto' is the noun for a sudden fright or shock.

Literally 'to give the reason/right' to someone. Used when conceding a point or siding with someone's argument.

Borrowed from boxing/martial arts, used figuratively to mean becoming less vigilant or cautious.

Distinct from 'confiar en', though both mean to trust. 'Fiarse de' often carries a more instinctive, gut-feeling sense of trust or distrust, and appears very frequently in spoken dialogue about suspicion.