The Collaborative International Dictionary
Subsign
Subsign \Sub*sign"\, v. t. [imp. & p. p. Subsigned; p. pr. &
vb. n. Subsigning.] [L. subsignare; sub under + signare to
mark: cf. F. soussigner. See Sign.]
To sign beneath; to subscribe. [R.]
--Camden.
Wiktionary
subsign
n. (context semiotics English) A lower-level sign. vb. (context transitive archaic English) To sign beneath; to append a signature to.