The Collaborative International Dictionary of English v.0.48:

Sen \Sen\, n.
   A Japanese coin, worth about one half of a cent.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sen \Sen\, adv., prep., & conj. [See Since.]
   Since. [Obs.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

sen
    n 1: a fractional monetary unit of Japan and Indonesia and
         Cambodia; equal to one hundredth of a yen or rupiah or riel

Bouvier's Law Dictionary, Revised 6th Ed (1856):

SEN. This is said to be an ancient word which signified justice. Co. Litt.
61 a.