1. Adjective.  (context, of a route, terrain, etc.) Incapable of being passed over, crossed, or negotiated.
  2. Adjective.  (context, of an obstacle) Incapable of being overcome or surmounted.
  3. Adjective.  (context, of currency) Not useable as legal tender.

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This entry was last updated on RefTopia from its source on 3/20/2012.