An addendum, a useful word:
An ••ostensive definition•• is a definition by example. No bright line that distinguishes “is” from “isn’t;” instead, we have a set of examples we agree clearly fit the word, then ask, “How does this other thing resemble the examples?”
Some words are best defined ostensively. “Sandwich” is a great example. You can have silly fun playing with the boundary conditions — A quesadilla is a sandwich!! A hot dog is a taco!! — but to get pendantic about that fun is foolish.