Ultrasonic, having a frequency too high to be audible.
Greater than the speed of sound (in the same medium, and at the same temperature and pressure).
An aircraft that can travel at the speed of sound.
Ineffectual; slow-witted, slow to act, or dull.
Late; overdue or delayed.
Moving with a slow pace or motion; not swift.
A piece of paper given to students who are late to class.
An instance of a student's being marked as tardy by a teacher on the teacher's attendance sheet.