ALLOGRAPH

allograph

(noun) a signature written by one person for another

allograph

(noun) a variant form of a grapheme, as ‘m’ or ‘M’ or a handwritten version of that grapheme

Source: WordNet® 3.1

Etymology

Noun

allograph (plural allographs)

A variant form of a letter (or other grapheme).

A signature made by one person for another (compare autograph).

Source: Wiktionary

Al"lo*graph, n. Etym: [Gr. -graph.]

Definition: A writing or signature made by some person other than any of the parties thereto; -- opposed to autograph.

Source: Webster’s Unabridged Dictionary 1913 Edition