Capture unknown word

Hi all
I have been using rhasspy for a while now and I would like to extend my system a little.
I can’t seem to find this here or in the docs.
I’m sure it has come up before.
Is there a process to have an intent with one random word.

like
[word_lookup]
(what is the meaning of) ???

I only want to capture that one word

Thanks and sorry if I have used the wrong search words and this is clearly in the documentation or here.