Indirect coupling refers to a relationship between two systems or components that interact through a third intermediary. This means that instead of directly affecting each other, the two systems influence one another through this intermediary, which can be another system, component, or even a shared environment. For example, in a biological ecosystem, plants and animals may not interact directly, but they are indirectly coupled through the food chain. The plants provide food for herbivores, which in turn are preyed upon by carnivores, creating a network of interactions that connect them without direct contact.