Once upon a time, when I was an itty bitty grad student, I had an appointment with an immunology PI to ask to be involved in their research.
One of the first questions they asked me was, what's inflammation?
"You want the layman's answer or the real answer?"
"Both."
"The layman's answer is that set of cellular and biochemical reactions involved with infections and their resolution."
"And the real answer?"
"There's no such thing. 'Inflammation' is the set of cellular and molecular biology that immunologists discovered before everyone else did. There isn't a single molecule in the body that isn't involved in a wide variety of functions, and there isn't a single function -be it extracellular remodeling, monitoring of cells for expression of abnormal proteins, cell signaling, cell life cycle regulation, etc. - that doesn't hook into a hundred different functions in a hundred different contexts. 'Inflammation' refers to the lens of the person studying the thing, not the thing."
I got a happy smile and a welcome handshake with that answer.