The Collaborative International Dictionary of English v.0.48:

Duffel bag \Duffel bag\
   A sack to hold miscellaneous articles, as tools, supplies, or
   the like.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

duffel bag
    n 1: a large cylindrical bag of heavy cloth; for carrying
         personal belongings [syn: duffel bag, duffle bag,
         duffel, duffle]