The eight-lettered mantra of Narayana and the five-lettered mantra of Siva are the two greatest mantras of Hindu religion, next only to the Gaayatri mantra. Volumes can be written about the name Narayana, which is to be pronounced as naaraayaNa, though we shall stick to the more popular spelling, Narayana. nara means aatman, that is, brahman itself. All the elemental principles emanated from it, therefore they are naara. They are the effects of the Supreme which is the Ultimate Cause, the Cause of all causes, for them all. The cause always pervades the effect. Without a cause, there is no effect. Wherever there is an effect there must be a cause. Therefore the effects which are the naaras are pervaded by the original cause, which is brahman. This is what is indicated by the word Narayana. This name has been extolled to the skies in all the puranas and other scriptures. The Tamil veda says: it is the word which does all the good more than the mother. Whatever sense experiences one goes through, whether it is inside or outside, everything is pervaded by the Lord Narayana -- says the Upanishad. They are all in me (mayi te) and I am in them (teshu chaapyaham) says the Lod in the Gita (IX - 29). That everything is in Him is the bahir-vyaapti ( = transcendence; bahih = outside). That He is in everything is the antar-vyaapti (= immanence; antah = inside). Transcendence and Immanence are the T and I of the TIP of the Iceberg that is the Godhead. These two are now in capsule form in the single name Narayana, where one takes the meaning of ayana as support, or base or substratum. Ayana also indicates both the 'means' (= upaaya) and the 'end' (= upeya). So Narayana may mean 'He (= His name) is the means and He is the end' as also 'He (= His Grace) is the means and He is the end'
When talking about the significance of the name Narayana it is not possible to conclude without mentioning the story of Ajamila, that occurs in the sixth skanda of Srimad Bhagavatam. Ajamila was once a very noble brahmin, performing his duties and prescribed rituals most sincerely and was also a good husband, good son and good father. Once when he was in the forest to gather the fuel-wood for his rituals, he fell for a woman, heart and soul. Actually the woman was one of very low morals. From that time onwards he lived with her, abandoned his family and his own parents. He got ten children by her, made a living and supported this large family by blackmailing rich people, by cheating, fraud and gambling. He was particularly fond of the youngest child, Narayana, by name. The attachment to the child was so pronounced that whether he was eating, drinking, relaxing or working, he would always want Narayana to be by his side and partake of his food or participate in his enjoyment. When finally the call from Yama, the God of Death came, it came suddenly and in his agony he called his child to his side and cried: O Narayana, come to me and be with me. The messengers of Yama who almost got him in their noose suddenly found from within his heart four well-clad beautiful angel-like figures preventing the messengers of Yama from discharging their duty. An intense conversation ensued between the messengers of Yama on the one side and the messengers of Narayana - because that is what they were - on the other side. The latter declared:
This Ajamila, though he has forgotten his real natue, has pronounced the four-syllabled name of God Narayana at the time of death and by that very action has done the praayaschitta (repentance act) for all his sins. A thief of gold, a drinker of wine, a betrayer of a friend, a killer of a brahmin, one who commits adultery with the wife of his guru, a killer of a woman or of a king, or of a cow or of his father -- all these grat sinners have been declared to be absolved by the recitation of God's name bwecause by that very act he becomes God's protege and deserves to be under His care. Not all the repentance-rituals of the scriptures can wash a man's sins off as much as the name Narayana can. The repentance acts only purify past sins; they do not guarantee the non-commission of future sins or the non-repetition of the same acts for which the atonement-ritual was done. But taking God's name on the tongue will eradicate the vaasanas that are the causes of sinful acts and so the future actions and his entire character will change. There are rituals and rituals (for atonement and purification) of different degrees -- easy ones for elementary sins and difficult ones for deeper sins. But as far as taking the Lord's name is concerned it is only one. The one name of God absolves and purifies sins of all kinds, small or large. Even when he has uttered the name wihthout really intending to call the Supreme Lord, it purifies him just as wood is burnt by fire, irrespective of the intent.
After all this explanation by the messengers of Vishnu the messengers of Yama felt overpowered and they went back to their overlord. In the meantime Ajamila came back to his senses and remembered all the conversation that went on in the presence of his subtle body between the messengers. He was about to say something, when the messengers of Vishnu also disappeared. It was quite a while before he could take stock of the situation. Here he was. alive and kicking, by the mercy of God Narayana, whose name he had just taken on the point of death, not in remembrance of the Lord but in passionate affection of his child. If this single act of the utterance of a four-syllable word Narayana can make such a difference to life after death, what larger worlds of fullness and majesty he may not conquer by really leading a noble life of Dharma in the memory of the Lord? -- so thought Ajamila. And that very moment he renounced everything to which he was attached, went to Benares and engaged himself in austerities and meditation and in due time reached the abode of the Lord. ( For more discussions and details on the Ajamila story go to 22.14).