earnestly; strenuously ...1632 obs. rare
irregular from Latin obnixe adv. strenuously,
from obnixus struggled against, pa. pple. of obnixi to struggle or strive against
FIRST DOCUMENTED USE
1632 - See example below
"...At the sight of each new Moone, (I speake it credibly) bequeath their Cattell to her protection, obnixiously imploring the pale Lady of the night, that shee will leave their Bestiall in as good plight, as shee found them."
From: The Totall Discourse of the Rare Adventures
and Painefull Peregrinations of Long Nineteene Yeares Travayles.
from Scotland, to the most Famous Kingdomes in Europe, Asia, an Affrica
By: William Lithgow, 1632
• A New English Dictionary on Historical Principles, James Murray, 1887-1933