The Collaborative International Dictionary of English v.0.48:

kos \kos\ n.
   an Indian unit of length having different values in different
   localities.

   Syn: coss.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

kos
    n 1: (in India) a unit of length having different values in
         different localities [syn: kos, coss]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

KOS
       Kent On-Line System (OS)