"Oglinda aceasta este frumoasă."

Translation: This mirror is beautiful.

[Kefir87]

Another Slavic loandword. "Ogląda" (which sounds more or less like "oglonda") means "he/she watches" in Polish.

[Schattenparker]

English "glint" and "glance" seem also to be related to the same indo-european roots as the Slavic lineage of "oglindă/oglinzi".

(I found that hint with German "Glanz" = shine here: https://www.dwds.de/wb/Abglanz)

Which says that people and their languages were mixing all the time... (Wouldn't it be fun to know if some words from the Neandertals survived somehow that way, too?)

[conlaff]

So, nouns with "this" require a definite article, and "that" does not?

[abcdefg-1]

"That mirror" = "Oglinda aceea," so it does require the definite article.