1. direct and unreserved in speech; straightforward; sincere:
2. without inhibition or subterfuge; direct; undisguised:
a frank appeal for financial aid.
3. Pathology. unmistakable; clinically evident:
4. Archaic. liberal or generous.
5. Obsolete. free.
6. a signature or mark affixed by special privilege to a letter, package, or the like to ensure its transmission free of charge, as by mail.
7. the privilege of franking letters, packages, etc.
8. a franked letter, package, etc.
9. to mark (a letter, package, etc.) for transmission free of the usual charge, by virtue of official or special privilege; send free of charge, as mail.
10. to convey (a person) free of charge.
11. to enable to pass or go freely:
to frank a visitor through customs.
12. to facilitate the comings and goings of (a person), especially in society:
13. to secure exemption for.
14. Carpentry. to assemble (mill-work, as sash bars) with a miter joint through the moldings and a butt joint or mortise-and-tenon joint for the rest.