adjective
Definition: Describing a type of relationship where one organism benefits while the other is not harmed or helped.
Example: The commensal bacteria in our gut help with digestion without affecting our health negatively.
noun
Definition: A living thing that benefits from a relationship with another organism, where one gains an advantage and the other is not harmed.
Example: The clownfish is a commensal that lives among the tentacles of sea anemones, gaining protection without harming them.