a. [ OE. fifte, fifthe, AS. fīfta. See Five. ]
Fifth monarchy men (Hist.),
Fifth wheel,
n.
n. [ from a statement during the Spanish Civil War (1936) that the Falange had four columns of soldiers marching on the city, and a fifth column “already there” (i.e. sympathizers inside the Republican lines). ]
adv. In the fifth place; as the fifth in order. [ 1913 Webster ]