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

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

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.