Bigger dictionary for Firefox spell checking

[endolith]

I'm tired of legitimate words being underlined in red in Firefox because the built-in dictionary is so small.  Can we add a larger dictionary as an add-on?

[Megamind]

I'm kinda bummed this has such low kudos. I wrote out a comment recently using common gaming terms (laning, gank (and its variants), MOBA, inting, etc) and all of them get underlined. Even words like "checkboxes" get underlined, similar to the above's "militaries", so I'm guessing it can't even handle inflections. 😞 I understand that I can't expect parity with Chrome because $$$ (and I'm assuming it's some complex ML/AI driven checker that Firefox will struggle to match) but it's another point on the list of things which makes Firefox feel like a downgrade ...