NOUN (3)

1. a cleric who holds more than one benefice at a time;

2. a philosopher who believes that no single explanation can account for all the phenomena of nature;

3. someone who believes that distinct ethnic or cultural or religious groups can exist together in society;

The Collaborative International Dictionary of English v.0.48:

Pluralist \Plu"ral*ist\, n. (Eccl.)
   A clerk or clergyman who holds more than one ecclesiastical
   benefice. [Eng.]
   [1913 Webster]

         Of the parochial clergy, a large proportion were
         pluralists.                              --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pluralist
    n 1: a cleric who holds more than one benefice at a time
    2: a philosopher who believes that no single explanation can
       account for all the phenomena of nature
    3: someone who believes that distinct ethnic or cultural or
       religious groups can exist together in society