The Tibetan term for renunciation is  ngepar jungwa; nges par ’byung ba, which literally means “certainty of release.” Ngepar is short for ngepar shepa, meaning to have certain, decisive knowledge from within; in this case, it refers to having certainty that the nature of worldly existence is suffering. In addition to this certainty, there is the heartfelt wish to be released, jungwa, from this suffering. One must gain confidence in the fact that the nature of cyclic existence in samsara is suffering, together with having the powerful wish and intention to be free of this suffering. This is what is known as the thought of renunciation. 

-- Nyoshul Khen Rinpoche