1.Definition: characterized by careless unconcern

"The heedless generosity and the spasmodic extravagance of persons used to large fortunes"

Related Adjective(s):reckless

2.Definition: marked by or paying little heed or attention

"We have always known that heedless self-interest was bad morals; we know now that it is bad economics", "Heedless of danger", "Heedless of the child's crying"

Related Adjective(s):unheeding