Curt, brusque (6)
I believe the answer is:
abrupt
I believe this is a double definition.
'curt' is the first definition.
(both can mean rudely brief)
'brusque' is the second definition.
(I've seen this before)
(Other definitions for abrupt that I've seen before include "Gruff" , "Terse, curt" , "Sudden, maybe rude" , "Terse and sudden" , "Rough and quick" .)