Source : Webster's Revised Unabridged Dictionary (1913)

Sen \Sen\, adv., prep., & conj. [See {Since}.]
   Since. [Obs.]

Sen \Sen\, n.
   A Japanese coin, worth about one half of a cent.

Source : WordNet®

sen
     n : a fractional monetary unit of Japan and Indonesia and
         Cambodia; equal to one hundredth of a yen or rupiah or
         riel