careless 1 antonyms and opposites of careless. Adjective — Not paying enough attention, so that mistakes or accidents happen. Synonyms for careless cursory derelict heedless irregardless irrespective lash lax neglectful negligent reckless regardless remiss slack slapdash sloppy slovenly slipshod unfaithful Antonyms for careless meticulous ← Back to the full definition of careless
