frank, n.
1. (cap.) A member of the Germanic people who conquered Gaul in the 6th century. • France received its name from the Franks.
2. A signature, stamp, or mark affixed to mail as a substitute for postage. [Cases: Postal Service 15. C.J.S. Postal Service and Offenses Against Postal Laws §§ 18–19.]
3. The privilege of sending certain mail free of charge, accorded to certain government officials, such as members of Congress and federal courts.
— Also termed (in sense 3) franking privilege. [Cases: United States 12. C.J.S. United States §§ 27–28.] — frank, vb.