The word "weren't conscientious" refers to the absence of a sense of duty or responsibility in someone's behavior or attitude. Some antonyms that could be used to describe this behavior or attitude are careless, negligent, irresponsible, inconsiderate, uncommitted, unreliable or indifferent. These words suggest a lack of attention, concern or commitment to a task, duty, or responsibility. An individual who is not conscientious may disregard ethical or moral standards, neglect their obligations or fail to complete tasks to satisfactory standards. In contrast, being conscientious is an admirable quality that is valued in many areas of life, including the workplace, education or personal relationships.