(archaic) Under which or what.
Secondly, how do dictionary makers decide words?
To decide which words to include in the dictionary and to determine what they mean, Merriam-Webster editors study the language as it’s used. They carefully monitor which words people use most often and how they use them.
Also know, how do you spell orgue? “Orgue.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/orgue.
Also question is, what does Commotrix mean?
These defined what. could be called “inkhorn terms” – commotrix. (“a maid that makes ready and unready her.