D defs.my
Entry 1 sense Webster, 1913

Undersign

· Un·der·sign · IPA
01 v. t. To write one's name at the foot or end of, as a letter or any legal instrument.
  1. 1.
    To write one's name at the foot or end of, as a letter or any legal instrument.
Phrases & compounds
The undersigned — the person whose name is signed, or the persons whose names are signed, at the end of a document; the subscriber or subscribers.