offhand

Without preparation or forethought; extemporaneously.

Performed or expressed without preparation or forethought.

At once; without deliberation or premeditation; without previous preparation or practice.

From the hand; without the support of a rest.

Without study or premeditation; impromptu: as, an offhand remark; an offhand speech.

Free and easy; unstudied or unconventional: as, an offhand manner.

Instant; unprepared; ready; extemporaneous; unrehearsed

without planning or thinking ahead

careless; without sufficient thought or consideration

curt, abrupt, unfriendly