Say it briefly: Abbreviations

We English speakers have several options for condensing what we say or write into a more compact and modern form. I'm not just talking about slangy, super-relaxed text-speak, either. We might say info in place of the longer information or cop instead of the slightly dated, or perhaps just more firmly rooted in British culture than American, copper. But while cop has a slangy feel, info has become more acceptable even among button-down types.

Abbreviation is a general term that can apply to any shortened word form. This term does not specify how conciseness is achieved. Other terms go a step further. They describe a particular way of cutting down words and phrases into their smaller counterparts. These terms are not interchangeable. Here are a few types of abbreviation.

contractions
In a contraction, letters that represent sounds that have tended to fade from our informal spoken language are simply left out of the written form. An apostrophe appears in the place where those letters would have been. Contractions often come in part from modals or helping verbs.

cannot --> can't
would not --> wouldn't
should have --> should've

Portmanteaus
A portmanteau word is a type of contraction, but it's special in two ways: There is no apostrophe, and the word parts are often connected at a letter common to both original words. For example,

smoke + fog --> smog [connected at the common letter o]

initials or initialisms
The word initial means "first." Initialisms are, strictly speaking (more on that below), abbreviations made up of the first letter of each word in a phrase.

FBI ("Federal Bureau of Investigation")
IBM ("International Business Machines")
LBJ ("Lyndon Baines Johnson")

I confess, calling abbreviations made up of letters that are not at the beginning of a word "initials" bothers me irrationally because of my name. I maintain that because I have only four names (first, middle, maiden, and married), I have only four initials. But I have a capital L in the middle of my first name. For as long as I can remember, I have been correcting documents that treat that L as an extra initial--at the expense of my actual, legal initials on forms that have space for only three or four. In the face of common near-initialisms like IV ("intravenous") and DNA ("deoxyribonucleic acid"), however, mine is a futile argument.

acronyms
An acronym is an initialism (or near-initialism) with class: When spoken aloud, it is not spelled letter by letter but pronounced smoothly as though it is a single word.

AWOL ("absent without leave"): pronounced "A-wall"
NATO ("North Atlantic Treaty Organization"): pronounced "NAY-tow"

Sometimes acronyms become so ingrained in language that they become words visually by losing their capital letters. Scuba ("self-contained underwater breathing apparatus") and radar ("radio detection and ranging") are two notable examples.

Your turn, readers. What are your favorite abbreviations that have come into common and acceptable use, even in more formal settings? Are there cases when using an abbreviation causes confusion instead of efficiency? Have unfortunate pronunciations resulted from using only initials as an abbreviation? (I can recall a few of those.) Chime in!