See On a —— Basis.
A present participle is a verb ending in -ing, and is called dangling when the subject of the -ing verb and the subject of the sentence do not agree. An example is “Rushing to finish the paper, Bob's printer broke.” Here the subject is Bob's printer, but the printer isn't doing the rushing. Better would be “While Bob was rushing to finish the paper, his printer broke.” (Pay close attention to sentences beginning with When ——ing.)
One way to tell whether the participle is dangling is to put the phrase with the participle right after the subject of the sentence: “Bob's printer, rushing to finish the paper, broke” doesn't sound right.
Not all words ending in -ing are participles: in the sentence “Answering the questions in chapter four is your next assignment,” the word answering functions as a noun, not a verb. (These nouns in -ing are called gerunds.) [Revised 3 August 2001.]
A dash (publishers call it an “em-dash” because it's the width of the letter m) is used to mark a parenthesis — like this — or an interruption. Don't confuse it with a Hyphen, although you can use two hyphens -- like this -- for dashes in your papers. (Most word processors have a special symbol for the dash, which you can use if you like; note, though, that it's not always possible in every program, and they don't always come through in E-mail.) Whether dashes should have — spaces — around — them or not—like—this is a question of house style.)
There's nothing wrong with a few dashes here and there, but too many of them will make your writing less formal. Using them where other punctuation marks are proper is okay in informal correspondence, but out of place in most other kinds of writing. [Entry revised 11 June 2001]
There's no one way to spell out dates; it's a matter of house style. In American usage, “September 14, 2004” (usually with a comma) is most common when you're spelling things out, and “9/14/04” (or “09/14/04”) when you're abbreviating. In much of the rest of the world, “14 September 2004” (usually without a comma) and “14/9/04” (or “14/09/04”) are more common. Other possibilities abound, including some that put the year first. Whatever you do, be consistent; and if your audience might be international, avoid using just the digits: “04/03/02” could be 3 April 2002, 4 March 2002, 2 March 2004, and so on. [Entry added 14 Sept. 2004.]
The word comes from a particularly gruesome practice in ancient Rome: when a legion engaged in mutiny, the rulers would execute every tenth man as a warning to the rest. Literally, then, it means to kill one out of ten. It's now commonly used for anything that wipes out a large proportion of a population. Some readers dislike the more extended sense, so use it with care. [Entry added 9 May 2007.]
I was surprised to discover that demagogue has been a verb since 1656 — I assumed it was a recent mutation. Still, it's an ugly, jargony verb, one that no one but dimwitted politicians will miss. [Entry added 12 July 2005.]
A denotation is a word's literal meaning; a connotation is the full range of suggestions and associations that go with it. Dictionaries usually give a word's denotations, but are often less useful in revealing connotations; a good writer, though, will be conscious of the hidden meanings carried by every word. Think, for instance, about the phrases make love, have intercourse, make whoopie, copulate, mate, and screw — they all refer to the same act, but they're not at all interchangeable; when you need to refer to the act, you have to figure out which set of associations will have the desired effect on your audience. (By the way, I'm very fond of Farmer & Henley's Historical Dictionary of Slang, which offers some more creative options, sadly neglected today: to dance the blanket hornpipe, under-petticoating, to perform the act of androgynation, to do jumble-giblets, to have a wollop-in, to dive in the dark, to Adam and Eve it, to strop one's beak, to make the beast with two backs — that last one's Shakespeare's.) See Diction, Dictionaries, and Audience. [Entry revised 21 April 2006.]
A clause is just a group of words with a subject and a verb, a part of a sentence. Some groups of words can get by on their own without any help: these are called independent. Others can't stand alone; either they don't have their own subject and verb, or they're subordinated to another part of the sentence: these are dependent. (A hint: dependent clauses often begin with words like if, whether, since, and so on; see Conjunctions.) Knowing the difference can help you figure out when to use commas.
For example: in the sentence “Since we've fallen a week behind, we'll skip the second paper,” the first part — “Since we've fallen a week behind” — is dependent, because it can't be a sentence on its own. The second part — “We'll skip the second paper” — does just fine on its own; it's an independent clause. The independent clause can be a sentence without any help from the Since clause.
Once upon a time I knew a lot about diagramming — thank you, Mr. Gallo. Alas, it's all gone now. That's to say, I still remember the principles — the parts of speech and their relations — but I've long since forgotten all the symbols, the dotted lines, the left-leaning slashes, all that sort of thing.
There's a good site, though, by Gene Moutoux, who long taught English and foreign languages, called Sentence Diagrams: One Way of Learning English Grammar. Check it out. [Entry added 20 Jan. 2005; link updated 19 May 2011.]
Dialogue has been a verb for a long time; Shakespeare used it in 1607. But today its use as a verb sounds very jargony, and I encourage you to avoid it. The American Heritage Dictionary put the question to its usage panel; fully ninety-eight percent found it objectionable. [Entry added 12 July 2005.]
Diction means simply “word choice.” English teachers probably mention it most often when there's a problem with the level of diction. The English language sports many near synonyms, groups of which may share more or less the same denotation, but which differ in connotation. And sometimes these connotations can be arranged hierarchically, from high to low. Think of warrior (high diction), soldier (middle), and dogface or grunt (low); or apparel (high), clothes (middle), and duds (low). Higher diction often involves Latinate words, and lower diction Germanic, but not always.
And it's not just a matter of high, middle, and low diction; there are many possible registers — scientific, flowery, bureaucratic, vulgar. The important thing is to be consistent: if you jump at random between levels of diction, you're likely to confuse your audience. And that's a bad thing.
No writer can survive without a good dictionary. I'm fond of the American Heritage Dictionary, 4th ed.; it not only provides clear definitions, but refers controversial usage questions to a panel of experts who vote on whether they're acceptable. (It's also available for free on-line.) For more serious historical work, there's nothing like the Oxford English Dictionary (or OED, as it's universally known) — this twenty-volume juggernaut not only provides remarkably comprehensive definitions, but it shows how words have been used throughout their history. Anyone who writes for a living — or even a hobby — should get to know the OED.
But although dictionaries are indispensable, you have to know how to use them. Be careful not to accord to them more authority than they claim for themselves: they're works of reference put together by people, not stone tablets engraved by God. The old argument that something is “not a word” because it doesn't appear in “the” dictionary (as if there were only one dictionary), for instance, is downright silly. Any pronounceable combination of letters to which someone assigns a meaning can be called a word; the question is whether it's a good word — by which, of course, I mean an appropriate word. Many dictionaries list words like ain't or irregardless; that doesn't mean you can use them with impunity in formal writing. Pay close attention to the usage notes — “Nonstandard,” “Slang,” “Vulgar” — and be sure you choose the right word.
Dictionaries are also more concerned with denotations than connotations, and you're a fool if you think a dictionary entry amounts to a Get-out-of-Jail-Free card in any writing problem. Some dictionary may define gook as an Asian or queen as a gay man, but you can point to the dictionary all you like (“It's sense 3b!”) without convincing anyone it's appropriate or inoffensive. Be sensitive to the associations your words carry to your audience.
Avoid, by the way, referring to “Webster's,” which has no specific meaning — any dictionary can use the name. Merriam-Webster, on the other hand, is a specific company that produces well-regarded dictionaries. Besides, dictionary definitions at the beginnings of papers rarely add anything to the discussion. A favorite line from The Simpsons, where Homer wins the First Annual Montgomery Burns Award for Outstanding Achievement in the Field of Excellence: “Webster's Dictionary defines ‘excellence’ as ‘The quality or condition of being excellent.’” A well-chosen nugget of information from a dictionary is wonderful, especially when you're engaging in close reading, but you just waste your introduction if you use it to state the obvious. [Revised 17 December 2006.]
The word different is often redundant, as in several different options or many different participants. Since you can't have several of the same option or many of the same participant, several options and many participants will do nicely.
Note that the phrase “different than” gets under many people's skin. In most cases, “different from” is a little more proper. So “Grunge is different from heavy metal” (but “Things are different than they were”). Brits sometimes use “different to,” but that sounds odd to American ears. [Entry revised 1 June 2004.]
A direct object is the thing (or person) acted on by a transitive verb. The indirect object is used most often for the recipient in verbs of giving. Examples are clearer than definitions.
“I took the paper” — the paper is the direct object, because the verb took acts on the paper; the paper is the thing that was taken. “I called her this morning” — her is the direct object, because the verb called acts on her; her is the person who was called.
“I gave him my suggestions” is a bit more complicated. Here him is an indirect object, because him isn't the thing that was given; I gave suggestions, and I gave them to him. Suggestions is the direct object, him the indirect object.
The words are often used interchangeably, but traditionalists prefer to keep them separate. Both mean “without interest,” but “interest” has several meanings.
Disinterested means “without a stake in” — without a bias, impartial. Uninterested means “indifferent” or “without a care about” — you just don't give a damn.
You can be disinterested in something but not uninterested, and vice versa. For instance, because I'm not a betting man, I don't stand to gain or lose anything in the outcome of most sporting events; I might still enjoy watching a game: I'm disinterested but not uninterested. Conversely, I might not care about the intricacies of tax policies, but I certainly have a stake in the outcome: I'm uninterested but not disinterested. [Entry added 12 Jan. 2005.]
The traditional past-tense form of dive is dived. Although dove is common in speech, it's probably safer to stick with dived in writing. See also Sneak, Sneaked, Snuck. [Entry added 12 Jan. 2005.]
In many languages, double negatives are perfectly acceptable: Spanish no sé nada, literally “I don't know nothing,” means “I know nothing” or “I don't know anything.” And in England, shortly before 1400, Chaucer wrote of his Knight, “Ther nas no man no wher so vertuous,” which is literally “There wasn't no man nowhere so virtuous” — which we'd have to render today as “There was no man anywhere so virtuous.”
So even in English, double negatives were once common. In Standard Modern English, though, they're problematic. Since the seventeenth century or so, people have been applying strict logic to these double negatives, suggesting that they “cancel each other out.” Take the idiomatic Spanish phrase, “I don't know nothing”: logic says that if you don't know nothing, then you must know something. As a result, it's usually best to avoid double negatives in formal writing.
As to whether two negatives “make a positive,” that's a little more troublesome: you need to be sure you have an audience that will recognize your meaning. Ambiguity is always a danger in writing: there are two ways to pronounce “I couldn't do nothing,” one of which is an informal way of saying “I couldn't do anything,” the other “I couldn't sit by and do nothing, but had to get involved.” Without the clues provided by spoken emphasis, though, your readers might not know which of these meanings you want to convey. Be careful. [Entry added 12 July 2005.]
Some folks object to the phrase due to when it's used prepositionally: “He stayed home due to the flu.” I don't much like it myself — I find it inelegant, and avoid it in my own speech and writing — but it's so widespread that there's little point campaigning against it anymore. (Note, though, that it's due to, not do to.)
But the big, ugly phrase due to the fact that really has to go — not because of some abstract grammatical law, but because it's a stuffy, five-syllable way of saying “because.” Remember, economy is a virtue. [Entry added 21 Dec. 2004.]