Is there a word similar to "iff" meaning "one and only one"?

I find the word "iff" for "if and only if" quite helpful for brief statements, but is there a similar one meaning "one and only one"?

edit In light of the ambiguities some of the answers so far hint at, here's an example I'd like to shorten:

Of the statements x, y, z, one and only one statement is true

should become

xorne of the statements x, y, z is true

where xorne is the sought word.

I have never come across such a word. My best ideas for replacements are: Precisely one, Exactly one, just one.

Sidenote: Some Authors prefers "if and only if" over "iff", since it can be easy to forget to show both ways. So maybe it is a good thing that there is no shorthand, if indeed there is none.

John H. Conway has said that whenever he writes "iff", he finds himself compelled to also write "thenn" (ie, "then and only then!") for parallel emphasis in both parts of a statement. (It's only fair, after all, given that the statement asserts the parts' logical equivalence.)

I see no reason that we can't follow his lead (as well as consonant-doubling precedent) and introduce, say, "onne" into the mathematical vernacular.

Edit. According to @AndreasBlass, Conway (unsurprisingly) beat me to it.

Edit. User @Someone else posted a sourced answer linking Conway to "onne", then deleted that answer for being a "duplicate" of mine. OP and I find the reference(s) helpful, so I'll quote the post here. (If @Someone has an objection ---or if this is a violation of some StackExchange policy--- I can delete it.)

J H Conway of Princeton introduced "onne" for "one and only one". (Reference: Margie Hale: "Essentials of Mathematics: Introduction to Theory, Proof, and the Professional Culture")

I have seen this a few times in books and scholarly papers, although it is obviously much less common than "iff".

In a follow-up comment, @Someone wrote:

Here's a second (although possibly not very reliable) source for the same thing - MathForum post.

You can see it written symbolicallly: $$ \exists ! $$ So like this:

$(\exists! x \in \mathbb N)( x^2=4)$