a. 1. Not thinking; not heedful; thoughtless; inconsiderate; as, unthinking youth. [ 1913 Webster ]
2. Not indicating thought or reflection; thoughtless. [ 1913 Webster ]
With earnest eyes, and round unthinking face, He first the snuffbox opened, then the case. Pope. [ 1913 Webster ]
-- Un*think"ing*ly, adv. -- Un*think"ing*ness, n. [ 1913 Webster ]