7 Advisories About Abbreviations

By Mark Nichol

Abbreviations are useful, but they can be wickedly tricky little widgets. Keep these points in mind when you truncate words and phrases:

1. a/an

This entry refers not to a or an as abbreviations but to which of the two indefinite articles should precede a given abbreviation. The choice depends not on the first letter of the abbreviation itself but on the sound of the first letter. Therefore, for example, you’d write “an MD after her name,” rather than “a MD after her name,” because the first letter in that abbreviation is pronounced “em” and should therefore be preceded by an.

2. Initials as Adjectives

“I went up to the ATM machine and put in my PIN number to check my IRA account.” And in relating this event, I made three errors. In each case, the last letter of the abbreviation stands for the noun following the abbreviation. This is a job for the Department of Redundancy Department!

3. Metric Abbreviations

Abbreviations for metric measurements either immediately follow the associated numeral (100m for “100-meter dash”) or follow a letter space (“2.2 kg = 1 lb.”); the latter style prevails especially when, as in the example given here, references to both metric-system and English-system measurements occur. But note the absence of periods following the metric abbreviations. Metric abbreviations are always lowercase — with one optional exception: Because of the resemblance of the letter l to the number 1, the abbreviation for liter is often uppercase or italicized, or, when handwritten, styled in cursive writing.

4. Periods

In abbreviations, periods are passe. Period. (Except not: e.g., i.e., etc. But mostly, yes.)

5. Plurals

Omit apostrophes with plural forms of abbreviations: “He has two PhDs,” “It lists various NGOs,” “They’re all NIMBYs.” Of course, if the style for the publication in question retains periods (but see the previous point), retain the apostrophe as well: “Several R.N.’s failed the test.”

6. Postal Symbols

Postal symbols are a prescribed set of two-letter abbreviations for states that are sometimes used as shorthand in nonpostal applications. In 1963, to make room for an innovation known as the ZIP code (which phrase has its own entry below), the US Postal Service advocated a two-letter form (CA, for example), but many people persist in incorrectly styling such abbreviations uppercase/lowercase (e.g., Ca.) or appending an extraneous period (CA.).

7. ZIP Code

Those clever folks at the USPS selected this name to imply that mail would arrive at its destination more speedily if the five-digit code was supplied, but ZIP actually stands for something — Zone Improvement Plan — so treat it with all caps.

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17 Responses to “7 Advisories About Abbreviations”

  • Paul

    “An SQL query” is the correct way to say it. It is correctly pronounced letter by letter, i.e. “S-Q-L” (Structured Query Language), not “Sequel”.

    Also, on the litre thing I always use a capital if I’m handwriting it (but this is almost always for my own benefit) but lower case when I type it, though I also always use a font which differentiates between a “1”, a lower case L, and also an upper case I, which is another which it can be confused with.

    Note also that in Britain we use “re” and not “er” on the end of such words – it certainly helps to avoid confusion when talking about things like gas and electricity meters.

  • Dale

    I just discovered this site. Thank you.

  • Round One

    Oops, mine too, dyslexia.

  • Mark Nichol


    Thanks for the technical addenda. I should have specified that I was dealing only with the nontechnical usages, though I think it is clear I’m referring to physical dimensions only, not other scientific units as well. Other than metric units of unusual magnitude (MUUM), and the optional exception for liter, metric abbreviations are lowercase.

  • Peter

    Abbreviations for metric measurements either immediately follow the associated numeral […] or follow a letter space

    They should be separated with a thin space.

    Metric abbreviations are always lowercase — with one optional exception: Because of the resemblance of the letter l to the number 1, the abbreviation for liter is often uppercase or italicized, or, when handwritten, styled in cursive writing.

    No. Units based on people’s names (which is most of them: ampere, kelvin, hertz, joule, newton, pascal, watt, tesla, etc.) are always capitalized (A, K, Hz, J, N, Pa, W, T, etc…though the names are not capitalized when written out in full). The only ones not capitalized, that I can think of, are five of the seven base units: meter (m), (kilo)gram (kg), second (s), candela (cd), and mole (mol).

    Also, prefixes bigger than “kilo” are upper case.

    Liter can be upper or lower case ‘l’, but the cursive ‘l’ is not accepted.

  • Mark Nichol


    I’d say “an es-ay-es-ee,” but I don’t know whether that pronunciation or the other is more prevalent.

  • Mark Nichol


    I’ve heard only “ess-que-ell,” but maybe tech geeks out there pronounce it otherwise. Anyone?

  • Mark Nichol


    Yes, American’s refer to the imperial system as the English system. Also, if I ever knew about capitalizing very large metric units, I’d forgotten.

  • Mikey

    I have one minor correction to make regarding Point 3, metric measurements.

    The case of the prefix in the metric mesurements is actually quite important. In some situations, the case of the suffix is also critical.

    For instance, the prefix in lower case ‘m’ means “milli” or one, one-millionth of the unit. Capital ‘M’ means “mega” or one million units. (http://www.unc.edu/~rowlett/units/prefixes.html)

    The correct use of metric prefixes is absolutely critical for technical writers, or anyone who works with engineers, or in communication.
    For example concerning speed of internet connections, the suffix with lower case ‘b’ referrs to “bits” of data – the smallest unit of data. Upper case ‘B’ referrs to “Bytes” of data where one Byte = 8 bits. So if a connection is referred to as 1 Mb (one Megabit) it is 1/8th the speed of a 1MB (one Megabyte) connection.

    People writing in the IT industry frequently misuse the prefixes and suffixes all the time. Sometimes deliberately to obscure that the actually speed, storage capacity, or bandwidth of connections.

  • marilyn cram-donahue

    Thanks so much for standing up for me. I’ve been preaching to students for years about listening to the sounds of words. The use of “an” before an abbreviation beginning with a vowel sound makes sense, if for no other reason than it is easier on the vocal chords to pronounce it that way.

    As for the sase problem. I seldom hear it pronounced as an acronym. People usually look panicked and stutter “uh-es-ay-es-ee.” Try it as an initialism for yourselves. “An es-ay-es-ee” comes out smoothly, and it’s easy to say. Thanks, Stephanie, for bringing this up.

    I love this site. Love it! Love it! (My studets are learning to love it.)

  • Ken


  • Stephanie Orges

    Concerning point #1, what’s your take on the abbreviation SASE? Some people pronounce it as an acronym (“a sase”), some as an initialism (“an es-ay-es-ee”). Everything I’ve read on it says it could go either way; which one is more common/accepted?

  • Cliff

    What about abbreviations that also have a name like SQL. Some will read it as ess-que-ell whereas others read it as sea-qwell. So which is better, “a SQL query” or “an SQL query?”

  • Ed Buckner

    The engineer in me came to full alert when I read about the metric abbreviations. Stephen beat me to the point on capitalized prefixes. One should also look out for zany mixed abbreviations in scientific literature such as Btu for British Thermal Units and pH as a measure of acidity/alkalinity. I have often seen million, when not using metric units, abbreviated as MM. The second letter in a chemical symbol is also not capitalized such as Pb for lead or Hg for mercury.

  • Rebecca

    Thanks for the reminder!

  • Stephen

    Thanks so much for this, particularly points 1, 2, and 5, which irritate me when I see them written incorrectly.

    I’m quite interested by your point 3, too. Do you really refer to pounds (lb), miles, etc. as English-system measurements? In England, I’ve always heard them referred to as Imperial measurements.

    Also, metric system measurements aren’t always lowercase. The metric base units are lowercase, but some prefixes are correctly written in uppercase, in particular M for mega- (a million) as opposed to m for milli- (a thousandth). Day to day, we don’t tend to talk about megametres (Mm) or megagrams (Mg), but they are nevertheless correct terms.

  • sap erp modules

    These 7 steps are very important in learning the abbreviations and pronunciations of the words in the right way. Good article about explaining the importance of it.

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