NOUN (1)

1. either of two different animal or plant species living in close association but not interdependent;


ADJECTIVE (1)

1. living in a state of commensalism;

The Collaborative International Dictionary of English v.0.48:

Commensal \Com*men"sal\, n. [LL. commensalis; L. com- + mensa
   table: cf. F. commensal. Cf. Mensal.]
   1. One who eats at the same table. [Obs.]
      [1913 Webster]

   2. (Zool.) An animal, not truly parasitic, which lives in,
      with, or on, another, partaking usually of the same food.
      Both species may be benefited by the association.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Commensal \Com*men"sal\, a.
   Having the character of a commensal.
   [1913 Webster]

WordNet (r) 3.0 (2006):

commensal
    adj 1: living in a state of commensalism
    n 1: either of two different animal or plant species living in
         close association but not interdependent