Where does “idealis” come from?

idealis (Latin) comes from Latin idea, from Ancient Greek ἰδέα, from Ancient Greek εἴδω, from Proto-Indo-European weyd- — to see.

Ancestry of “idealis”, step by step

Step	Language	Word	Meaning
1	Latin	idea	idea; prototype
2	Ancient Greek	ἰδέα	form, shape; look, appearance, semblance; type,...
3	Ancient Greek	εἴδω	to see; I see
4	Proto-Indo-European	weyd-	to see

idealis — Etymology, Origin & Word History | Etymology Explorer