UNTHINKING

lumpish, lumpen, unthinking

(adjective) mentally sluggish

thoughtless, uncaring, unthinking

(adjective) 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’”

unreflective, unthinking, unthoughtful

(adjective) not exhibiting or characterized by careful thought

thoughtlessly, unthinkingly, unthinking

(adverb) in a thoughtless manner; “he stared thoughtlessly at the picture”

Source: WordNet® 3.1

Etymology

Adjective

unthinking (comparative more unthinking, superlative most unthinking)

Without proper thought; thoughtless.

Showing no regard; careless or unconcerned.

Verb

unthinking

present participle of unthink

Source: Wiktionary

Un*think"ing, a.

1. Not thinking; not heedful; thoughtless; inconsiderate; as, unthinking youth.

2. Not indicating thought or reflection; thoughtless. With earnest eyes, and round unthinking face, He first the snuffbox opened, then the case. Pope.

– Un*think"ing*ly, adv.

– Un*think"ing*ness, n.