Smear Campaign

An acronym is a word, or wordoid, formed from the initials of a phrase and then pronounced as a word. (If you can't or usually don't pronounce it as a word, but instead spell it out, as in "I.B.M.", it's called an initialism.) "Scuba" is one of the most famous examples of an acronym: it's a full-fledged word, but it was originally an abbreviation of Self-Contained Underwater Breathing Apparatus. "Laser" is another: it's condensed out of Light Amplification by Stimulated Emission of Radiation. Since they're words, they're often spelled in lower-case, though when they're proper nouns, they're often capitalized: "NATO", for example, the North Atlantic Treaty Organization.

But sometimes a word seems as if it might be an acronym when it isn't. Take a look at this flubbed sentence from this story in The Consumerist:

We're not sure which is weirder, American Airlines wanting to look at your PAP test or your lawyer writing a press release about it.

Capitalizing "Pap" makes it look like an acronym; maybe it stands for "Pelvic And Prenatal"!

Nope. It's not an acronym at all: it's a shortened version of a person's name, that person being Giorgios Papanikolaou, the doctor who invented the test. (With a name like that, you can see why it was shortened in the English language.)