Is there a difference between acronyms and abbreviations? Yes. An abbreviation is any shortened or contracted form of a word or phrase. An acronym is a specific type of abbreviation formed from the first letters of a multi-word term, name, or phrase, with those letters pronounced together as one term. OPEC—or the O(rganization of) P(etroleum) E(xporting) C(ountries)—is an acronym because we pronounce it as one word, oh-pek. This is distinct from an initialism, which is another form of abbreviation in which each letter is pronounced separately, like FBI. To complicate the issue, there are hybrid forms—part initialism, part acronym—like CD-ROM and JPEG—for which one term is as good as the other.

These terms have strangely diverse histories. Abbreviation is a relatively old word and has been used since the 1400s. It is the noun form of the word abbreviate from the Late Latin abbreviātus meaning “shortened.” Initialism arose at the end of the 1800s, combining initial with the suffix -ism, which forms nouns from verbs like baptism. Acronym is relatively new. Some claim it was first used in 1943 by scientists at Bell Laboratories from a blending of acro- meaning “tip” (like acropolis) and -nym meaning “word” (like synonym). Though there is also a record of the word being used as early as 1940 from the German term akronym.

Today abbreviations—both initialisms and acronyms—are commonly used in text messages and online writing (from informal social media to high-quality web journalism). Though LOL and OMG are the poster children of textspeak, dozens of other useful abbreviations have recently arisen that are both efficient and expressive. TLDR, an initialism standing for “too long; didn’t read,” is now a common tag for media posts, a subreddit, and the name for a WNYC podcast.

What are some acronyms and initialisms you’ve heard lately?