The Collaborative International Dictionary
Overthwartly
Overthwartly \O"ver*thwart"ly\, adv.
In an overthwart manner; across; also, perversely. [Obs.]
--Peacham.
Wiktionary
overthwartly
adv. 1 (context obsolete English) In an overthwart manner; going across. 2 (context obsolete English) perversely