allograph

from WordNet (r) 3.0 (2006)

allograph
    n 1: a variant form of a grapheme, as `m' or `M' or a
         handwritten version of that grapheme
    2: a signature written by one person for another

from The Collaborative International Dictionary of English v.0.48

Allograph \Al"lo*graph\, n. [Gr. ? another + -graph.]
   A writing or signature made by some person other than any of
   the parties thereto; -- opposed to {autograph}.
   [1913 Webster]

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