The Collaborative International Dictionary of English v.0.48:

Sou \Sou\, n.; pl. Sousor. [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.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sous \Sous\, Souse \Souse\ (F. s[=oo]; colloq. Eng. sous), n.
   A corrupt form of Sou. [Obs.] --Colman, the Elder.
   [1913 Webster]