Negligent is an adjective of two genders that classifies that person or institution that acts negligently, that is, that is inconsiderate, careless, sloppy.
To be negligent is to show oneself insensitive, it is not to assume due responsibility in situations that demand some care and attention.
Being negligent is a characteristic of one who is indolent, lazy, inert, one who is absent at the time of performing his duties.
To neglect is to refuse to fulfill your function with determination, zeal and dedication.
Carelessly is the adverb so that it classifies a careless behavior or attitude. Ex: He left the house and carelessly left the door open.
Some synonyms negligent are: languid, slow, careless. On the other hand, some of your antonyms are: diligent, careful, considerate and applied.
careless, reckless and impetuous
Within the scope of work safety, there are the concepts of negligence, recklessness and malpractice. These are different concepts but they are often confused because they can have similar negative results.
The negligent person makes a mistake, due to lack of attention and despite having to be careful so that it doesn't happen, has an attitude that allows the error or disaster to happen. For example, if a child dies after ingesting a toxic substance because that substance was left within reach by his father, we can say that the father was negligent.
A reckless individual is one who takes a dangerous attitude, takes unnecessary risks, and puts his own integrity and that of others at risk. Recklessness has a stronger component of intentionality, because the person knows he shouldn't do what he's doing. For example, a person who drives a car at excessive speed on a rainy day is being reckless.
The person who is inexperienced, or who commits malpractice, makes an error due to lack of knowledge in a certain area. In the case of a professional accused of malpractice, the error is made due to lack of aptitude or knowledge in the area in question.
