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.
UNTHINK
Un*think", v. t. Etym: [1st pref. un- + think.]
Definition: To recall or take back, as something thought. Shak.
Source: Webster’s Unabridged Dictionary 1913 Edition