Treachersome

Tom was now holding forth hotly upon the "onparalleled [sic] rascality and treachersome villainousness" of the Opposition in the Ontario Legislature. Elizabeth, her eyes alight, ran swiftly past the gate towards her father.

Source: wiktionary

I do wish you'd come away, Princey ! ” said the little girl anxiously. “I b'lieve he's one of those treachersome dogs that you never know what they mean ― There!

Source: wiktionary

Ko-kosh was treachersome but I could outwit his kind. I kept a close watch. He stole back my knife but I got it again. I wanted a gun. I couldn't come south without I had a gun and I couldn't hunt my food. We went north on the Lake of the Hurons.

Source: wiktionary

Kid Curry dismounted. “Stay put whilst I shed some light on the subject. The clay footing around here is sort of treachersome when it's this wet. [...]”

Source: wiktionary