The term used to describe an organism's ability to respond to its environment is stimulus response. This capacity allows organisms to detect and react to changes or stimuli in their surroundings, facilitating survival. Responses can be behavioral, such as fleeing from threats, or physiological, like adjusting body temperature. Adaptation to environmental stimuli is crucial for maintaining homeostasis and ensuring the organism's well-being, significantly impacting fitness and reproductive success in fluctuating ecosystems.