The Collaborative International Dictionary
Subsigning
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
subsigning
vb. (present participle of subsign English)