What term describes a phenomenon where one organism secretes a substance that inhibits the growth of another organism?

The correct term for the phenomenon where one organism secretes a substance that inhibits the growth of another organism is allelopathy. This process occurs when a plant or microorganism releases chemical compounds into the environment, which can be detrimental to the growth or survival of nearby competing organisms, particularly other plants. Allelopathic interactions are common in ecosystems where certain plant species produce allelochemicals that can affect seed germination, root growth, or overall plant health of neighboring species.

While parasitism involves one organism benefiting at the expense of another, and amensalism generally refers to a situation where one organism is inhibited while the other is unaffected, they do not specifically involve the secretion of inhibitory substances. Similarly, competition involves two organisms striving for the same resources, but it doesn't directly relate to the secretion of compounds that inhibit growth. Therefore, allelopathy distinctly describes the inhibitory chemical interactions that are central to this question.