Though only large dictionaries include it and the Oxford English Dictionary says it is obsolete or archaic, candent has retained a toe-hold on usage in the sense of something glowing, as if with white heat, largely in SF and fantasy novels whose authors delight in obscure language.
Neal Asher used it in The Voyage of the Sable Keech: “The rock blew apart in a candent explosion, hurling pieces of itself out into space”, as did Robert Asprin in his fantasy anthology Shadows of Sanctuary: “Shards punched through knife holes and widened them to let quicklime spill down in a candent stream”. Clark Ashton Smith wrote it into The Black Abbot of Puthuum: “Noon, with its sun of candent copper in a blackish-blue zenith, found them far amid the rusty sands and iron-toothed ridges of Izdrel”, and Poul Anderson borrowed it for The Long Night: “The stars were scattered about in their myriads, dominantly ruby and ember, some yellow or candent, green or blue.”
It was almost completely replaced by incandescent in the first decades of the nineteenth century. Both are relatives of candour, candid and candidate, the linking thread being the concept of whiteness. The last three are from Latin candidus, white (Roman candidates for public office wore togas rendered white so they could be easily seen in the Forum, which had nothing at all to do with white then being figuratively the colour of innocence and frankness). Candent is from the verb candere, to be white or to glow, and incandescent derives from the related verb incandescere, to become white-hot.