constructed language, basically someone sits down and actively plans out/constructs the features they want a language to have instead of language naturally evolving like most languages come about. There's a good chink of people who dabble in conlangs, @bitter_dandelion 🌟 is one such person (and the person whose username I most remember)

wow thats really cool and sounds very hard

oh yeah agree on both fronts, I find conlangs cool but am not one of the conlang peeps on here (you will see random things to do with that rock up eventually on here)