1. not giving sufficient attention or thought to avoiding harm or errors
2. done or said without thinking or effort

Examples

• She made a careless mistake on the math test.
• His careless driving caused the accident.
• Don’t be careless with your expensive phone.
• The careless worker left tools scattered everywhere.
• He gave a careless shrug and walked away.
• Her careless comment hurt his feelings.
• The student’s careless handwriting was hard to read.