repentinamente
/repenˌtinaˈmente/ · B2 · adv
suddenly
⚡ repentina + mente: repent(ino) 'sudden' + -mente adverb ending = suddenly
Repentino means sudden, from Latin repens (sudden, unexpected). Add -mente, the Spanish equivalent of English -ly, and you get repentinamente: in a sudden way. Same root as English repent-less 'abrupt' sense in Latin repente, 'all at once'.