> Because while stuttering is a momentary mode of speech, stutter is the symptom/condition we suffer from. You have it reversed. A stutter is a single, momentary occurrence while *stuttering* describes the condition and often multiple occurrences. I'm not a linguist and I'm also a few drinks in right now, but usually when you add on the "-ing" suffix it describes a process (e.g. "I am singing" or "I am jumping")/an ongoing action.