NOUN (3)

1. all the gods of a religion;

2. a monument commemorating a nation's dead heroes;

3. (antiquity) a temple to all the gods;

The Collaborative International Dictionary of English v.0.48:

Pantheon \Pan*the"on\, n. [L. pantheon, pantheum, Gr. pa`nqeion
   (sc. 'iero`n), fr. pa`nqeios of all gods; pa^s, pa^n, all +
   qe`os a god: cf. F. panth['e]on. See Pan-, and Theism.]
   1. A temple dedicated to all the gods; especially, the
      building so called at Rome.
      [1913 Webster]

   2. The collective gods of a people, or a work treating of
      them; as, a divinity of the Greek pantheon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pantheon
    n 1: all the gods of a religion
    2: a monument commemorating a nation's dead heroes
    3: (antiquity) a temple to all the gods