twee·dle·dum and twee·dle·dee \ˌtwēdəlˈdəmənˌtwēdəlˈdē\noun Usage: usually capitalized both Ts Etymology:tweedle (I) + dum (imitative of a low musical note) & dee (imitative of a high musical note) : two objects, persons, or groups differing superficially or insignificantly : a practically indistinguishable pair