NOUN (3)

1. an outline or synopsis of a play (or, by extension, of a literary work);

2. a setting for a work of art or literature;
- Example: "the scenario is France during the Reign of Terror"

3. a postulated sequence of possible events;
- Example: "planners developed several scenarios in case of an attack"

The Collaborative International Dictionary of English v.0.48:

Scenario \Sce*na"ri*o\, n. [It.]
   A preliminary sketch of the plot, or main incidents, of an
   opera.
   [1913 Webster]

WordNet (r) 3.0 (2006):

scenario
    n 1: an outline or synopsis of a play (or, by extension, of a
         literary work)
    2: a setting for a work of art or literature; "the scenario is
       France during the Reign of Terror"
    3: a postulated sequence of possible events; "planners developed
       several scenarios in case of an attack"