Abrupt means sudden and unexpected, in a way that feels rude or jarring. Nothing led up to it.
It describes endings, changes and manner, so an abrupt halt, an abrupt change of subject and an abrupt reply are all standard. Applied to a person it means curt, and being abrupt with somebody is a mild social offence. Landscape uses it plainly, since an abrupt slope drops away sharply. The adverb abruptly is common in narrative, and abruptness is the noun for the manner.
1adjectiveabruptSudden and unexpected.
“The music came to an abrupt stop.”
2adjectivecurtCurt and unfriendly in manner.
“He was abrupt to the point of rudeness.”
Too few real examples of this word to estimate which sense is commonest.
Abrupt is broken off. Latin abrumpō joins ab, away, to rumpō, to break, so an abrupt ending is a snapped one and an abrupt manner is somebody breaking off mid-courtesy.
Proto-Indo-European
*Hrewp-
Latin
abruptus
English, today
abrupt
Built from
Borrowed from Latin abruptus. First attested in 1583. Borrowed from Latin abruptus (“broken off”), perfect passive participle of abrumpō (“break off”), formed from ab (“from, away from”) + rumpō (“to break”).
Etymology from Wiktionary, CC BY-SA