NOUN (2)

1. any very successful means of achieving a result;

2. a magical command; used by Ali Baba;

The Collaborative International Dictionary of English v.0.48:

Sesame \Ses"a*me\, n. [L. sesamum, sesama, Gr. ????, ???: cf. F.
   s['e]same.] (Bot.)
   Either of two annual herbaceous plants of the genus Sesamum
   (Sesamum Indicum, and Sesamum orientale), from the seeds
   of which an oil is expressed; also, the small obovate,
   flattish seeds of these plants, sometimes used as food. See
   Benne.
   [1913 Webster]

   Open Sesame, the magical command which opened the door of
      the robber's den in the Arabian Nights' tale of "The Forty
      Thieves;" hence, a magical password.

   Sesame grass. (Bot.) Same as Gama grass.
      [1913 Webster]

WordNet (r) 3.0 (2006):

open sesame
    n 1: any very successful means of achieving a result
    2: a magical command; used by Ali Baba