I'm only half-joking. If the language you're using doesn't have a word for the concept you wish to express, I sort of feel like you're justified in borrowing a word from another language.
There's "salut" which means "hi" but considered to casual to greet your neighbors, especially if you live in a big building and don't know them by name. So you basically have to know what time it is before greeting them. (plus it's not like there's an official cut-off)— Anne-Laure Le Cunff (@anthilemoon) September 10, 2020