negligent
NEG-lih-juntadjMeaning failing to take the care you should
Memory hook NEGLECT-GENT. The gent dozes on the park bench while his dog digs up the flower bed: he neglects the dog he should be watching. He is negligent.
The negligent landlord ignored the broken stair for months.
In context The night guard was found negligent: he had dozed through his whole shift while the alarm light on the back door blinked for three hours.
Similar careless, neglectful, lax, remiss
Opposite careful, attentive, diligent
From Latin neglegens, from neglegere, “to disregard, to fail to care for,” the same source as neglect.