English Lesson 19: Correct Use of A.M. and P.M. for Time
August 2nd, 2008
Over the past few weeks, I have been receiving several search queries about the “correct use of am and pm” or similar variants. Although I already know about standard time conventions, I have always wondered about whether or not there are any established grammatical rules for writing the 12-hour clock designations. After spending at least three hours researching this earlier today, it appears that there is no single hard-and-fast rule for expressing a.m. or p.m. when referring to time. The majority of the grammar-based sites that I encountered listed several variants. Some used capital letters or periods while others did not, but most of these sources agreed that all of these variants were acceptable as long as your usage remains consistent throughout your writing.
Eventually I ran across the Associated Press Stylebook guidelines, which state that for journalistic copy we should use the lowercase letter with period format and write the abbreviations as a.m. and p.m. without spaces between the letters or periods. When expressing an actual time, there is one space between the numerical value and the abbreviation, so for example three o’clock in the afternoon would be written as 3 p.m. Since we bloggers (at least those of us who are serious about our work) often like to think of ourselves as journalists, it’s probably a good idea for me to stick the AP standards on this when writing articles. However, for informal writing it doesn’t seem to make much of a difference.
Meanwhile, there were two other questions that came up frequently in searches regarding proper time expression. Here are the answers to these:
Last night I received a query from a searcher at Ask.com who wanted to know about the correct use of passed and past. Since I had already included this pair of homophones in my list of future post ideas, I might as well use this one for the current week. I have seen people confuse these words on web page copy enough to justify writing up a short tutorial on this so that webmasters can get past the relatively mundane task of worrying about grammar errors and can instead concentrate on the really fun things like monetizing their websites and blazing their own trails to economic freedom.
This group of homonyms is an issue that I have wanted to cover for several weeks. There are few things that give me that “fingernails on the chalkboard” feeling more than seeing someone spam a forum or email address by advertising their “web sight”. Now that I have worked through most of the others on my list, I hope to provide some enlightenment for people who are still misusing these words and unwittingly displaying their ignorance all over the Internet.
Trying to figure out whether to use the indefinite article a or an before a noun can be tricky for inexperienced English users. Many people seem to think that you should use a before a consonant and an before a vowel, but it is not quite that simple. The actual rule is that a is used before a consonant sound and an before a vowel sound — these do not always match up with the letter itself! For example, one of the most common mistakes I have been seeing recently is the use of “a hour” instead of “an hour”. The latter is correct because the word hour actually begins with an o (vowel) sound; the h is silent. Conversely, we would say “a Ouija board” instead of “an Ouija board” because Ouija is pronounced with a w (consonant) sound. 

Recently I have been seeing the two homonyms roll and role used incorrectly on forums and message boards, so in this week’s lesson I will explain the distinctions in their meanings so that readers can avoid confusion. The word roll has many meanings - some dictionaries list more than twenty - and can be used as either a noun or a verb. In the interests of time and brevity, I will quickly review the most common, easily distinguished meanings here:
Due partly to over-reliance on spell checkers, incorrect usage of both lose and loose has become common on the Internet and occasionally occurs in offline printed documents as well. Technically, the two words are not homonyms because there is a slight difference in pronunciation; the s in lose is pronounced with a z sound, while the s in loose is pronounced as we would normally expect. They also mean very different things, which is why it is important to learn the proper usage of these words so that one can avoid confusion and embarrassment. First, let us review the various meanings of lose. In all of these cases, the word is used as a verb.
One issue that few grammar guides seem to cover is the apparent confusion between the words ad and add. Although their meanings are quite different, whenever I see an instance of incorrect usage, it is sometimes difficult to tell whether the writer is simply making a typographical error or truly does not know which word to use. In either case, this is an important issue to clarify for Internet marketers because these two words are often used in sales copy, and mistakes made here can turn off potential buyers and lead to lower conversion rates.
The words affect and effect have been the source of many headaches and much confusion even among relatively experienced English users. This is understandable because the two words are very similar in pronunciation and spelling, yet have some subtle differences in meanings and usage that can be difficult to detect. Each word has one meaning that is far more common than the others, but the less common meanings are used often enough in print to create confusion for many readers. In this week’s lesson, I hope to clear things up by providing correct usage examples of the most common meanings first and then explaining some of the more esoteric or archaic usages of these words so that you can be aware of them when reading other publications.
A common mistake that inexperienced writers make when they try to compose original essays, articles, or blog posts is attempting to transcribe conversational English directly onto the printed page. This does not always work because the pronunciation of certain words and phrases can become corrupted with informal speech in ways that render them incorrect when written as standard English. A classic example of this phenomenon occurs when people write the phrase could have as “could of” or “coulda”. Similar errors occur with the phrases would have and should have.