The physician of the celestial gods; the deliverer from any evil or calamity. (Greek, pauo, to make to cease.)
A hymn to Apollo, and applied to the god himself. We are told in Dr. Smith's Classical Dictionary, that this word is from Paean, the physician of the Olympian gods; but surely it could be no honour to the Sun-god to be called by the name of his own vassal. Hermsterhuis suggests pauo, to make to cease, meaning to make diseases to cease; but why supply diseases rather than any other noun? The more likely derivation, me judice, is the Greek verb paio, to dart; Apollo being called the “far-darter.” The hymn began with “Io Paean.” Homer applies it to a triumphal song in general.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894