heedless

Synonyms: asleep at the switch daydreaming disregardful fast and loose feckless foolhardy goofing off impetuous imprudent inadvertent inattentive incautious inconsiderate irreflective neglectful negligent oblivious out to lunch precipitate rash reckless slapdash sloppy thoughtless uncaring unmindful unobservant unthinking unwary

Antonyms: attentive careful caring cautious concerned heedful observant thoughtful