A Scotch form (properly two words) of would no—that is, would not. (noun)
The Century Dictionary (Public Domain)
Use "wadna" in a sentence
"No. You ken fine your man or yoursel 'wadna' hae the name o 'stealin'."
"Ye suld munt up a muckle square of canvass, like Dick Tinto, and paint folks ainsells, that they like muckle better to see than ony craig in the haill water; and I wadna muckle objeck even to some of the Wallers coming up and sitting to ye."
"My ladyship did choose rather to look at the fine tree before me than to pass it by in hopes of a finer; so we walked beside the carriage till we should come to a point, from which, Donald assured us, we might, without scrambling, go as near the tree as we chose, “though he wadna advise us to go nearer than the highroad.”"