commensalism com·men·sal·ism (kə-měn'sə-lĭz'əm)
A symbiotic relationship in which one organism derives benefit and the other is unharmed.
A symbiotic relationship in which one organism derives benefit while causing little or no harm to the other. Examples of commensalism include epiphytic plants, which depend on a larger host plant for support but which do not derive any nourishment from it, and remoras, which attach themselves to sharks and feed on their leavings without appreciably hindering their hosts. Compare amensalism, mutualism, parasitism.