An arhat is one who has reached the goal of the early Buddhist path, a person in whom craving, aversion and delusion are wholly extinguished, and who will not be reborn.
The extinction of the defilements
The arhat has destroyed the mental defilements, the craving, aversion and delusion that bind beings to the round of rebirth, and has thereby attained liberation, so that at the end of this life the arhat is not reborn but passes beyond the cycle of birth and death, having accomplished what is to be accomplished on the path. The arhat is the ideal of attainment in the early Buddhist tradition and remains so in the Theravada, the disciple who has followed the teaching of the Buddha to its end and reached the same liberation.
The Theravada ideal and its critics
The centrality of the arhat is one of the points on which the Buddhist traditions divide, for the Mahayana came to hold up instead the ideal of the bodhisattva, who postpones final liberation to work for the salvation of all beings, and some Mahayana texts present the arhat as having attained a lesser or incomplete goal, so the standing of the arhat became a matter of doctrinal difference between the traditions. Within the Theravada, however, the arhat remains the summit of the path, and the tradition honours those held to have attained it. The arhat is not an office one is appointed to but a state that is attained through the full practice of the path, the realisation of the liberation the Buddha taught, and it stands at the centre of the early Buddhist understanding of the goal.