On'ry is an adjective and is a truncated version of the word "ornery". In the Baltimore, Maryland area, use of the term "on'ry" is quite common. In fact, in some of the Baltimore suburbs, reports have surfaced of locals beating down visitors for using "ornery" as opposed to the shortened, less complicated "on'ry". Attempts to question locals regarding this issue are usually met with a blank stare or an open-mouthed gaze downward.
Da-y-am...I'm gettin' on'ry 'cause da price a cigarettes done wen' up ag'in. An' they also jack'd up da price a Coors Light, uh, y'know, so ye'h I'm sure gettin' ev'n on'ryer now!