open, honest, and direct in speech or writing, especially when dealing with unpalatable matters

a long and frank discussion

to be perfectly frank, I don't know

stamp an official mark on (a letter or parcel) to indicate that postage has been paid or does not need to be paid

each cover will be franked with a specially designed postmark

the letter is franked 30 centavos

an official mark or signature on a letter or parcel, indicating that postage has been paid or does not need to be paid

a member of a Germanic people that conquered Gaul in the 6th century and controlled much of western Europe for several centuries afterwards