In Oxford Learner's Dictionary, under Achilles tendon, it says that
Achilles tendon = Achilles
Then the plural of 'Achilles tendon' is 'Achilles tendons'.
But, what is the plural form of "Achilles"?
In Oxford Learner's Dictionary, under Achilles tendon, it says that
Achilles tendon = Achilles
Then the plural of 'Achilles tendon' is 'Achilles tendons'.
But, what is the plural form of "Achilles"?
Why should you want "the plural of Achilles"? Nouns (common or proper) used as the non-final element of compounds don't usually take a plural ending; and if they do, they always take it. They don't change when the whole phrase is plural:
kitchen unit -> kitchen units.
cable provider -> cable providers.
and
glasses case -> glasses cases.
If you really want to talk about more than one Achilles, then most people would say "Achilleses", but people often aren't sure how to write it. I suspect some people would say "two Achilles" (like "two series").
Google finds around a dozen hits for "two achilles are", and only one for "two achilleses are". So I would say the consensus is that the plural of Achilles is Achilles.
However pluralizing achilles is so rare that I assume most people who do it aren't copying the plural form from things they've heard, but coming up with it de novo. So I would be very heistant to call achilleses wrong.