"I am no expert on this subject and am not taking a position but I thought the real question was whether a mute boy should have a bar mitzva at all or whether they are potur of mitzvahs as a cheresh." (source)

“I need a doctor's note as a ptur from going to class.” (Weiser)

“My ptur for coming late was that I couldn't get a ride back from out of town.” (Weiser)

"a ptur is a total exemption from the army for ur whole life." (source)