Plain English Meaning
A tower at an airport that handles both visual-flight traffic and aircraft flying on instrument flight plans, including issuing instrument clearances and coordinating with radar controllers.
Full Definition
Airport control towers that provide air traffic control services to aircraft operating under instrument flight rules in addition to handling visual flight rule traffic. IFR towers have the equipment, procedures, and authority to issue IFR clearances, separate IFR traffic in the immediate airport area, and coordinate with the TRACON or for and departures.