1851, "inconvenient thing that can't be got rid of," supposedly from the practice of the King of Siam of presenting one of the sacred albino elephants to a courtier who had fallen from favor; the gift was a great honor, but the cost of proper upkeep of one was ruinously expensive.
An unwanted or financially burdensome possession, or a project that turns out to be of limited value: “The new office building turned out to be a white elephant once the company decided to move its headquarters.”
Something putatively valuable, often a gift, that one does not want; an embarrassing piece of bric-a-brac: a wonderful collection of white elephants, trash, treasures
[1851+; fr the white elephant of Thailand, which, although it is sacred and royal, is also a clumsy sort of possession for one's house]