There isn't a specific definition of "word" in physics. The term "word" is not a commonly used concept in the field of physics.

It's possible you might be thinking of a related term, such as:

* Word Problem: This refers to a problem in mathematics or physics that is presented in a narrative form, requiring the student to translate the words into equations.

* Word Equation: This refers to a chemical equation written in words instead of chemical formulas.

* Work: A fundamental concept in physics, representing the energy transferred when a force acts on an object to move it.

Could you please provide more context or clarify your question? For example, you could specify where you encountered the term "word" in a physics context.