Amensal

Part of speech: adjective, noun

Definitions

1. Describing a relationship between organisms in which one lives on or within another while neither gains nor loses from the association
2. Relating to an organism that inhabits the same space as another without providing benefit or causing harm to its host
3. Pertaining to a neutral coexistence where one organism dwells in or upon another without affecting the other's welfare

Etymology: "Amensal" is a technical coinage from ecology, built from the prefix "a-" meaning "not" or "without" and "mensal", which means "of or belonging to a table." The table in question is the Latin "mensa," meaning "table" or "food," the same root that gives English words like "mensa" (a round table in a mess hall) and "commensal," meaning two organisms sharing a meal. The word's logic is a little mischievous. In biology, "amensalism" describes a relationship in which one species harms another without benefiting or being harmed itself. The term is therefore a kind of joke at the expense of the table: the organism that is damaged gets no seat at the meal, while its neighbour eats well and loses nothing. Ecologists needed a precise label for this one-way harm, and the "a-" prefix supplied the negation that "commensal" lacks.