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, offhanded. done or made offhand.

Glassmaking . working manually and without the use of molds

offhand blowing.

adjective

calculated , careful , considered , deliberate , planned , practiced

adjective

aloof , breezy , brusque , casual , cavalier , cool * , curt , easygoing , folksy , glib , informal , laid-back , mellow , perfunctory , unceremonious , unconcerned , uninterested , extemporary , extempore , impromptu , improvised , off the cuff * , off the hip , off the top of head , spontaneous , spur-of-the-moment , throwaway , unpremeditated , unprepared , unrehearsed , unstudied , without preparation , ad-lib , snap , abrupt , ad lib , autoschediastic , careless , chance , extemporaneous , hasty , improvisatorial , improvisatory , improviso , impulsive , unconventional , unplanned