The Collaborative International Dictionary
Whenceforth
Whenceforth \Whence`forth"\, adv.
From, or forth from, what or which place; whence. [Obs.]
--Spenser.
Wiktionary
whenceforth
adv. 1 (context formal English) From which place, time, or point forth; forth from which; onward from which. 2 (context formal interrogative English) Forth from what place, time, or point; onward from what place, time, or point.