unthinking
     adj 1: not exhibiting or characterized by careful thought [syn: {unreflective},
             {unthoughtful}]
     2: without care or thought for others; "the thoughtless saying
        of a great princess on being informed that the people had
        no bread; `Let them eat cake'" [syn: {thoughtless}, {uncaring}]
     3: mentally sluggish [syn: {lumpish}, {lumpen}]
     adv : in a thoughtless manner; "he stared thoughtlessly at the
           picture" [syn: {thoughtlessly}, {unthinkingly}] [ant: {thoughtfully}]
Source: WordNet® 2.0