英语语法：3 Abbreviations, Acronyms, and Initialisms

Grammar Girl here.

Today's topic is the difference between abbreviations, acronyms², and initialisms.

Unfortunately, you can't call any abbreviation made up of a phrase's first letters an acronym¹. Sometimes they are initialisms.

Acronyms

But let's back up. Any shortened form of a word is an abbreviation, for example, "etc." for "etcetera" and "Oct." for "October;" but acronyms are special kinds of abbreviations that can be pronounced as words, such as "NASA" (National Aeronautics³ and Space Administration) and "OPEC" (Organization of the Petroleum⁴ Exporting Countries). This makes acronyms a subset of abbreviations. All acronyms are abbreviations, but not all abbreviations are acronyms.

Initialisms

Initialisms are another type of abbreviation. They're often confused with acronyms because they are made up of letters, so they look similar, but they can't be pronounced as words. "FBI" and "CIA" are examples of initialisms because they're made up of the first letters of "Federal Bureau of Investigation⁵" and "Central Intelligence Agency," respectively, but they aren't usually pronounced as words. Insiders sometimes call the FBI "fibby" and the CIA "see-uh," but most of the world says "F-B-I" and "C-I-A," so they are initialisms.

Overview⁶

So remember:

Initialisms are made from the first letter (or letters) of a string of words, but can't be pronounced as words themselves. Examples include “FBI,” “CIA,” “FYI” (for your information), and “PR” (public relations).
Acronyms are made from the first letter (or letters) of a string of words but are pronounced as if they were words themselves. Examples include “NASA” and “NIMBY”(not in my backyard).
Abbreviations are any shortened form of a word.
Sometimes acronyms like "scuba⁷" become so common that they're accepted as words in their own right. "Scuba" was originally an acronym for "self-contained underwater breathing apparatus," but now dictionaries include it as a word.

ROFL?

Sometimes it's not clear whether a word is an initialism or an acronym because people say it different ways. Take the abbreviation you often see on the Internet for "rolling on the floor laughing." It's ROFL. I always pronounce it "roffle" as if it were an acronym, but when I surveyed my Twitter friends, I found that about half of them pronounce all the letters: R-O-F-L. So to people like me it's an acronym, and to people who say the letters it's an initialism. I don't have a good answer for what to call words like that. I guess we should use the broader category and just refer to them as abbreviations. And, of course, some people had to also point out that it's silly to say these kinds of text messaging/Internet acronyms out loud in the first place.

Punctuation⁸

You may be wondering whether you need to put periods after each letter in an acronym or initialism. There's no strict rule. Some publications put periods after each letter, arguing that because each letter is essentially⁹ an abbreviation for a word, periods are necessary. Other publications don't put periods after each letter, arguing that the copy looks cleaner without them, and that because they are made up of all capital letters, the fact that they are abbreviations is implied.

First Mention

Finally, when you're using any kind of abbreviation in a formal document, it's important to spell out the entire phrase the first time you use it and put the abbreviation in parentheses¹⁰ after the words so people know what your abbreviation means. This obviously doesn't apply to things like text messaging, but when you're writing in a professional way, you should never assume that people know what your abbreviation means. Using abbreviations without defining them makes your writing sound jargony and insular¹¹.

When you're spelling out the phrase, the first letters aren't capitalized unless they would normally be capitalized. For exampe, if you're writing about a measurement called the average daily volume and you put "ADV" in parentheses after the phrase, you don't capitalize the first letters of "average daily volume" in the text even though you capitalize the letters in the abbreviation. The letters in the words are lowercase just as they would be if you were writing them and not introducing an initialism.

That's all. Thanks for listening!

1 acronym   

n.首字母简略词，简称

参考例句：

• That's a mouthful of an acronym for a very simple technology.对于一项非常简单的技术来说，这是一个很绕口的缩写词。
• TSDF is an acronym for Treatment, Storage and Disposal Facilities.TSDF是处理，储存和处置设施的一个缩写。

2 acronyms   

n.首字母缩略词( acronym的名词复数 )

参考例句：

• Scratch the subject of defence and acronyms, abbreviations, and buzzwords fly out. 话题触及国防，缩合字，缩写字和行话就满天飞。 来自《简明英汉词典》
• Some acronyms as scientific terminology are used as a lexical item. 一些科学术语缩写用作词汇项目。 来自互联网

3 aeronautics   

n.航空术，航空学

参考例句：

• National Aeronautics and Space undertakings have made great progress.国家的航空航天事业有了很大的发展。
• He devoted every spare moment to aeronautics.他把他所有多余的时间用在航空学上。

4 petroleum   

n.原油，石油

参考例句：

• The Government of Iran advanced the price of petroleum last week.上星期伊朗政府提高了石油价格。
• The purpose of oil refinery is to refine crude petroleum.炼油厂的主要工作是提炼原油。

5 investigation   

n.调查，调查研究

参考例句：

• In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
• He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。

6 overview   

n.概观，概述

参考例句：

• The opening chapter gives a brief historical overview of transport.第一章是运输史的简要回顾。
• The seminar aims to provide an overview on new media publishing.研讨会旨在综览新兴的媒体出版。

7 scuba   

n.水中呼吸器

参考例句：

• I first got hooked on scuba diving when I was twelve.12岁时我开始迷上了带水中呼吸器潜水。
• While on honeymoon in Bali,she learned to scuba dive.她在巴厘岛度蜜月时学会了带水肺潜水。

8 punctuation   

n.标点符号，标点法

参考例句：

• My son's punctuation is terrible.我儿子的标点符号很糟糕。
• A piece of writing without any punctuation is difficult to understand.一篇没有任何标点符号的文章是很难懂的。

9 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。

10 parentheses   

n.圆括号，插入语，插曲（ parenthesis的名词复数 ）

参考例句：

• Irregular forms are given in parentheses . 不规则形式标注在括号内。
• Answer these questions, using the words in parentheses. Put the apostrophe in the right place. 用句后括号中的词或词组来回答问题，注意撇号的位置。 来自《简明英汉词典》

11 insular   

adj.岛屿的，心胸狭窄的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• Having lived in one place all his life,his views are insular.他一辈子住在一个地方，所以思想狭隘。