Reckless

a. [A-S. rēcelēas, O. D. roeckeloos.] Rashly or indifferently negligent; careless; heedless; mindless.

I made the king as reckless as them diligent. Sidney.

Synonyms—Heedless; careless; mindless; thoughtless; negligent; indifferent; regardless; unconcerned; inattentive; remiss.