WordWeb Online

1. With little or no preparation or forethought
   "offhand excuses";
   - ad-lib, extemporaneous, extemporary, extempore, impromptu, offhanded, off-the-cuff, unrehearsed
    
2. Casually thoughtless or inconsiderate
   "she treated most men with offhand contempt"; "an offhand manner";
   - offhanded

1. Without previous thought or preparation
   "couldn't give the figures offhand"; "we decided offhand to go to Canada";
   - offhanded, offhandedly
    
2. In a casually inconsiderate manner
   "replied offhand, his mind a million miles away";
   - offhanded, offhandedly

1. Without previous consideration
   "I don't know the figures off-hand";
   - ex tempore

See also: careless, cavalier, unprepared