I class a near miss as needing to take rapid and profound (been searching my head for a better word!) action to avoid a likely collision with an aircraft that you have suddenly and unexpectedly become away of, or something that has gone past you so fast that all you can do is exclaim "what the f*ck was that"!
Having spent 10 years operating off a strip with training, gliders and ag planes, maybe I have just learnt to "expect the unexpected" and work around it.
Dr 