Check on Definition 1 of 3Pro Tip 1/3Safety Reassurance Use 'check on' to show you are ensuring someone or something is safe or secure. I'll check on the doors to make sure they're locked. Pro Tip 2/3Quiet Concern If a person or situation has suddenly become quiet, 'check on' is used to investigate if everything is alright. She's too quiet. I'll go check on her. Pro Tip 3/3Caring Gesture 'Check on' can express care without being intrusive or overbearing. I'll check on Grandma after her doctor's appointment.