How do you spell Hannukah?
1942, short name for the group of drugs derived from sulfanilamide ("amide of sulfanilic acid," which is so called because it is a sulphonic derivative of the dye-stuff aniline), and shortened from that word. (The usual British English spelling is sulpha.)
sulfa sul·fa (sŭl'fə)
Of, relating to, or containing sulfanilamide or any sulfa drug.