abbreviation - это сокращение нескольких слов, а не словА

Abbreviation is the shortening of one or more words: nat’l / natl. / nat. = national -or- several words photo opp = photographic opportunity, B.C. = Before Christ. http://www.indiana.edu/~letrs/help-services/QuickGuides/oed-abbr.html

+++Grumbler

Интересно.
"аббревиатура" в русском - это всегда больше, чем одно слово - https://ru.wikipedia.org/wiki/%D0%90%D0%B1%D0%B1%D1%80%D0%B5%D0%B2%D0%B8%D0%B0%D1%82%D1%83%D1%80%D0%B0 (в отличие от https://en.wikipedia.org/wiki/Abbreviation)

Ah! And we also have ACRONYMS, which are comprised of the first letter of several words: EU = European Union, NATO, UNESCO, etc.

I know, but I think acronym is not JUST a combination of the first letters.
It's a special type of an abbreviation that is pronounced like a word. If so, I don't understand why EU is an acronym.

Hmm...
https://en.wikipedia.org/wiki/Acronym
"Although the word acronym is often used to refer to any abbreviation formed from initial letters, some dictionaries and usage commentators define acronym to mean an abbreviation that is pronounced as a word..."

That’s true. We say EU [ию], but UNESCO [юнэскоу]