Source : Webster's Revised Unabridged Dictionary (1913)

Sou \Sou\, n.; pl. {Sous}or. [F. sou, OF. sol, from L. solidus a
   gold coin, in LL., a coin of less value. See {Sold}, n.,
   {Solid}, and and cf. {Sol}, {Soldo}.]
   An old French copper coin, equivalent in value to, and now
   displaced by, the five-centime piece (1/20 of a franc), which
   is popularly called a sou.

Sous \Sous\, Souse \Souse\ (F. s[=oo]; colloq. Eng. sous), n.
   A corrupt form of Sou. [Obs.] --Colman, the Elder.