Dictionary:

commensal

  (kə-mĕn'səl)

Of, relating to, or characterized by a symbiotic relationship in which one species is benefited while the other is unaffected.

An organism participating in a symbiotic relationship in which one species derives some benefit while the other is unaffected.

[Middle English, sharing a meal, from Medieval Latin commēnsālis : Latin com-, com- + Latin mēnsa, table.]

Of, relating to, or characterized by a symbiotic relationship in which one species is benefited while the other is unaffected.

An organism participating in a symbiotic relationship in which one species derives some benefit while the other is unaffected.

1. living on or within another organism, and deriving benefit without harming or benefiting the host individual.
2. a parasitic organism that causes no harm to the host.

The noun has one meaning:

Meaning #1: either of two different animal or plant species living in close association but not interdependent

The adjective commensal has one meaning:

Meaning #1: (biology) living in a state of commensalism
  Pertains to noun: commensalism (meaning #1)