What is the term used to describe organisms that live in trees?

The term that describes organisms that live in trees is "arboreal." This classification is used for species that are adapted to life predominantly in the treetops or canopies. Arboreal organisms often have specialized physical traits that aid them in navigating the complex environment of trees, such as strong limbs, prehensile tails, or climbing adaptations. This term is commonly used in biology and ecology to discuss animal behavior, habitat preferences, and adaptations related to life in trees.

In contrast, terrestrial refers to organisms that live on land, aquatic pertains to those that inhabit water, and subterranean describes organisms that live underground. Each of these terms is specific to the environment in which the organisms thrive, but in this case, arboreal is the most fitting descriptor for tree-dwelling life forms.