Spencer (?), n. [OF. despensier. See Spence, and cf. Dispenser.] One who has the care of the spence, or buttery. [Obs.] Promptorium Parvulorum.
[1913 Webster]

Spencer, n. (Naut.) A fore-and-aft sail, abaft the foremast or the mainmast, hoisted upon a small supplementary mast and set with a gaff and no boom; a trysail carried at the foremast or mainmast; -- named after its inventor, Knight Spencer, of England [1802].
[1913 Webster]

Spencer mast, a small mast just abaft the foremast or mainmast, for hoisting the spencer. R. H. Dana, Jr.
[1913 Webster]