Good afternoon

The words for afternoon in Sp/Fr/It are each different, but each have a logic of their own.

In Spanish, the afternoon is the "late" time of the day - tarde (just like the "tardy slip" you get if you're late to class in school). It's feminine and, for the greeting it is of course plural:

Spanish tarde gives Buenas tardes (bweh-nahss tar-thase - pronounce the "th" as in "the").

The "late" time that is the tarde lasts until 8 or 9 p.m., when Buenas noches takes over.

In French, the afternoon is the time after noon but before evening. Makes sense. And here's the breakdown: The French word for noon is midi - midday (mi- = half + di = day - like Lat. dies and Sp. día). The word for after is après. Put them together and you get:

French après-midi becomes Bon après-midi (bohn ah-pray mee-dee).

By the way, Bonjour is more common, just as we're more likely to say "Hello" or "Good day" than "Good afternoon" in English.

In Italian, things are trickier. You know how we say "2 p.m."? That "p.m." stands for the Latin phrase "post meridio" - after noon. Now, imagine you're Italian and you're saying "post meridio" really fast. You just might get:

Italian pomeriggio gives Buon pomeriggio (bwohn poh-may-ree-joe). Buongiorno is probably more common.