Which word indicates something that is lasting or active throughout the entire year or many years?

The word "perennial" specifically refers to something that exists, continues, or is active throughout the entire year or for many years without interruption. In the context of nature, for example, perennial plants bloom and thrive each season, returning year after year, which emphasizes the idea of continuity over time.

This distinct characteristic of being long-lasting or enduring sets "perennial" apart from other terms. While "annual" pertains to something that occurs once a year, "temporal" relates to time but does not convey the idea of permanence. "Constant" refers to something that remains unchanged but does not specifically imply a duration that spans multiple years. Thus, "perennial" is the most fitting term to indicate a lasting presence or activity over a long period.