Source : Webster's Revised Unabridged Dictionary (1913)

Pertly \Pert"ly\, adv.
   In a pert manner.

Source : WordNet®

pertly
     adv : in an impudent or impertinent manner; "a lean, swarthy
           fellow was peering through the window, grinning
           impudently" [syn: {impertinently}, {saucily}, {freshly},
            {impudently}]