No one writes quite as delightfully about English as humorist and language expert Bill Bryson. In his introduction to Bryson’s Dictionary of Troublesome Words, after describing our language as "a merry confusion of quirks and irregularities that often seem willfully at odds with logic and common sense," he makes the sad but true observation that "many users of English continue to make usage decisions based on little more than durable superstitions and half-formed understandings."

It’s the "durable superstitions," or some of them at least, that concern us here. The following usage points are widely held, firmly believed, often repeated—and simply wrong.

MYTH: Though is an informal and undesirable variant of although and should be avoided.

FACT: Though and although are equally acceptable and nearly always interchangeable.

Some usage guides suggest that although is slightly more formal, but then add that though sometimes reads better, even in formal contexts. The upshot? Since both words are acceptable and more or less equally formal, choose whichever sounds better in a given situation.

MYTH: Till is an outdated, informal and undesirable variant of until and should be avoided.

FACT: Till and until are often equally acceptable.

No matter what its detractors say, till is a legitimate, acceptable word. As with though and although, many usage guides acknowledge that until is marginally more formal but then hasten to add that till is nonetheless at home in much formal prose. That said, until is considered the better choice to begin a sentence.

Incidentally, steer clear of the faux-abbreviation ’til, which is cute but wrong. It likely springs from the mistaken belief that till is a short form of until (in fact, till is the older word).

MYTH: As, since and while should signal relationships of time only.

FACT: In nearly all cases, as and since are acceptable synonyms for because, and while is an acceptable synonym for though or although.

The belief that we must reserve as, since and while for relationships of time is one of the most persistent usage myths around. Yet dictionaries and respectable usage guides agree: these words have perfectly acceptable non-temporal meanings as well.

These conjunctions are troublesome only on those rare occasions when they give rise to ambiguity. A sentence like this one, for instance, is worth a second look: "As the speaker droned on in a stupefying monotone, the audience grew sleepy." Did the audience grow sleepy because the speaker was droning on (causal), or while the speaker was droning on (temporal)? This sentence needs a clearer conjunction.

MYTH: Always use between with two entities and among with three or more.

FACT: Between is sometimes the only correct choice for three or more entities.

This myth is reinforced by the well-meaning but superficial treatment of between and among in general writing manuals. The usage chapters in these texts often present the simple usage rule (that is, the myth) and omit all discussion of the occasional, acceptable and unavoidable use of between to express certain relationships involving three or more things.

Among suggests a general sort of sharing and works well when the relationship is general ("discussion among the members," "you are among friends," "choosing among many cheeses"). But when three or more entities relate to each other individually and equally rather than collectively, or when the relationship is not general but reciprocal, between is the only word that will do. We must refer, for example, to a free trade agreement between (not among) Canada, the United States and Mexico; a contract between (not among) five interested parties; the partnership between (not among) the federal, provincial and territorial governments.

MYTH: It is incorrect to use the reason why; the structure is redundant.

FACT: The reason why is correct, idiomatic and only mildly redundant.

The reason why has a long history as an accepted construction. We have been using it, according to The New Fowler’s Modern English Usage (3rd ed., 1996), since the thirteenth century. The structure is no more redundant than the time when or the place where, constructions that for some reason catch far less flak than the reason why.

This myth may have so many adherents because of a similar cause-and-effect construction that usage and grammar guides routinely, and rightly, warn against: the reason why . . . is because, or just the reason . . . is because. In both structures the verb to be should be followed by that, not because.

MYTH: It is incorrect to use over to mean more than or in excess of.

FACT: Over is an acceptable substitute for more than or in excess of, particularly in combination with a number.

While scattered authorities (mostly American, says Fowler’s) criticize this usage of over, the majority consider it perfectly fine. Moreover, all major dictionaries list more than/in excess of as a standard definition of the word. According to Bill Bryson, "The stricture has been traced to Ambrose Bierce’s Write It Right (1909), a usage book teeming with quirky recommendations, many of which you will find repeated nowhere."

The only sure way to avoid the sticky web of usage myths is to have good resources on hand. An up-to-date dictionary is a must, and a reliable usage guide is a close second. Only reading, learning and questioning will lay our "durable superstitions" to rest.