The Collaborative International Dictionary of English v.0.48:
Henceforward \Hence`for"ward\, adv. From this time forward; from now into the indefinite future; henceforth. [1913 Webster +PJC]WordNet (r) 3.0 (2006):
henceforward adv 1: from this time forth; from now on; "henceforth she will be known as Mrs. Smith" [syn: henceforth, henceforward]