cavalierly, curtly, or brusquely: to reply offhand.
without previous thought or preparation; extempore: to decide offhand to take a trip.
informal, casual, curt, or brusque: an offhand manner.
Also, off·hand·ed. done or made offhand.
Glassmaking. working manually and without the use of molds: offhand blowing.
is always a great word to know.
So is quincunx. Does it mean:
1. short, shortly, abruptly. 3, 4. impromptu, extempore.