careless

marked by lack of attention or consideration or forethought or thoroughness; not careful

• “careless about her clothes”
• “forgotten by some careless person”
• “a careless housekeeper”
• “careless proofreading”
• “it was a careless mistake”
• “hurt by a careless remark”

effortless and unstudied

• “an impression of careless elegance”
• “danced with careless grace”

(usually followed by `of'') without due thought or consideration

• “careless of the consequences”
• “the proverbial grasshopper--thoughtless of tomorrow”
• “crushing the blooms with regardless tread”

showing an unthinking lack of consideration

• “a careless remark”