There isn't a specific concept in physics called "term declaration." It seems you might be mixing up some terminology or referring to a specific context.

To better understand what you're asking, could you please provide more context or information?

For example:

* Where did you encounter this term? (e.g., a textbook, lecture, online resource)

* What is the topic of discussion? (e.g., mechanics, electromagnetism, thermodynamics)

* What is the specific problem or situation you are trying to understand?

With more information, I can give you a more accurate and helpful answer.