What are the parents of your uncle's wife called?

Solution 1:

As far as I'm aware, there's no specific term in English for that relationship.

They are certainly not grandparents, that term applies only to the parents of your parents.

Solution 2:

No, there is no specific term.

We have in English grandparents (grandmother and grandfather), parents (mother and father), siblings (brother and sister), children (son and daughter), grandchildren (grandson and granddaughter), Aunts, uncles and cousins.

We can add multiple "great"s to grandparents or grandchildren to add extra generations, and add "first, second, third" to cousins for further generations before a common ancestor, and "once, twice, three times" removed for cousins who are not in the same generation as us.

We can also add "-in-law" for relationships by marriage, but this is restricted to very few situations. Your sibling's spouse or the sibling of your spouse is a brother/sister-in-law. Your spouses parents are father/mother-in-law and you're their son/daughter-in-law. No other uses for -in-law are in common usage.

Oh, and there are various alternative names for grandparents and parents, such as Nanny or Pops.

Other than that, there are no other kinship terms available.

In your situation, in order to use as few words as possible, if the Uncle is the blood relation (i.e. my parent's brother) I'd say "my Aunt's parents", or if the Aunt is the blood relation I'd say "my Uncle's parents". Even if people didn't know whether it was your Aunt or Uncle that was a blood relation, it'd be fairly obvious that you wouldn't refer to your own grandparents as "my Aunt's parents".