1. adjective
a) Late; overdue or delayed.
He yawned, then raised a tardy hand over his mouth.
b) ineffectual; slow witted, slow to act, or dullard
His tardy performance bordered on incompetence.
2. noun
A piece of paper given to students who are late to class.
The teacher gave her a tardy because she did not come into the classroom until after the bell.
Wikipedia foundation.