1900, but according to OED in use at Oxford as early as 1885, involuntary transposition of sounds in two or more words (such as "shoving leopard" for "loving shepherd," "half-warmed fish" for "half-formed wish," "beery work speaking to empty wenches," etc.), in reference to the Rev. William A. Spooner (1844-1930), warden of New College, Oxford, who was noted for such disfigures of speech. A different thing from malapropism.