Does "fighter's chin" have a meaning other than the figurative one?

Question

A character in the novel that I'm reading is described to have a fighter's chin. According to Wikipedia, it's a figurative term referring "to an ability to tolerate physical trauma to the chin or jaw without being knocked unconscious."

The way she's described makes it doubtful that it's being used for the figurative meaning. But I cannot find anything else on Google.

Can it mean a certain shape of a chin?

Here's the passage:

There was also fun in her, however. Her grey hair was gathered in a bun behind her, but there remained one sprightly forelock that flopped over her brow to the rhythm of her waddle. A hardy humour lit her brown eyes. Her mouth, set above a fighter's chin, seemed ready, given half a reason, to smile at any time.

Answer 1

You asked, "Does “fighter's chin” have a meaning other than the figurative one?"

The precise answer is "yes".

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But there is more to explain.

I trained at a boxing gym for several years, and can testify that a "fighter's chin" is a real thing.

However, in the passage's context, I would interpret that phrase to simply mean her mouth was tightly closed, because the chin is being used to describe the mouth.

Look in the mirror and do this:

1. Lightly bump your fist against your chin and notice how your jaw moves.
2. Tightly close your teeth together(also known as "clenching") so that your teeth and jaw are more stable.
3. Now lightly bump your fist against your chin again and notice the jaw does not move as much as before.
4. That is a fighters chin.
5. Now try to smile.

That's what I believe the writer means by "fighter's chin".