We'll break it to you gently: abrupt derives from abruptus, the past participle of the Latin verb abrumpere, meaning "to break off." Abrumpere combines the prefix ab- with rumpere, which means "to break" and which forms the basis for several other words in English that suggest a kind of breaking, such as interrupt, rupture, and bankrupt. Whether being used to describe a style of speaking that seems rudely short (as in "gave an abrupt answer"), something with a severe rise or drop ("abrupt temperature change"), or something that seems rash and unprecipitated ("made the abrupt decision to quit college"), abrupt, which first appeared in English in the 16th century, implies a kind of jarring unexpectedness that catches people off guard.