WordWeb Online

1. With little or no preparation or forethought
   "trying to sound offhanded and reassuring";
   - ad-lib, extemporaneous, extemporary, extempore, impromptu, offhand, off-the-cuff, unrehearsed
    
2. Casually thoughtless or inconsiderate
   "an offhanded manner";
   - offhand

1. Without previous thought or preparation
   - offhand, offhandedly
    
2. In a casually inconsiderate manner
   "replied offhanded, his mind a million miles away";
   - offhand, offhandedly

See also: careless, cavalier, unprepared