There are always people trying to expand the definition, but it's usually from more left-leaning critical schools of thought that want to classify landmines, sanctions or guns as WMD.
But in official usage, it's been pretty stable at those three.
A knife is not generally a weapons.
Saddam 100% had WMD's and was capable of making more.
But he didn't have an active program, stockpiles were small and there wasn't really a huge risk of him selling to 'terrorists' etc..
The misrepresentation was really one of magnitude and capabilities and especially how the information is presented.
"He Has WMD's" is very true and legitimate (different than 'he has a knife'), but obviously the misrepresented context makes it a giant lie.
To this end, I suggest that the US would do better in their public communications if they revealed some Twitterable/TikTokable visuals and graphics which highlighted the nature of some of the incursions, so as to more strongly make their case i.e. it's easier to believe 'something material' than accusations.