Spelling is the representation of a word in written form. This representation is usually approximate - there can be many different spellings for a single word; famously, Shakespeare is said never to have spelt his name the same way twice. Those interested in history may be amused to know that for a brief period between the invention of grammarians (late 18th century) and the invention of the Web (late 20th century) it was fashionable in elite circles to adopt a single standardized ("correct") spelling for each word. Of course, that fashion is now long past, but to commemorate it I present this quaint rant...
OK, I admit it. I'm an elitist pedant. I get really annoyed when I see basic grammar and spelling mistakes creeping into official documents and academic reports.
Don't misunderstand me - I'm also a radical, and I'm happy for people to change the rules if they really think their way is better. I've invented a couple of words myself. Nevertheless, just as the great modern artists studied the old ways before getting wild, radicals should understand the standard before replacing it. Deliberate language change is fine; simple typos are fair enough; ignorant mistakes are another thing entirely. It's true that OED English isn't standardized in the same way as ANSI C, but agreeing to use standard human language is a good idea for much the same reasons as agreeing to use standardized computer languages.
Therefore, in the spirit of bringing light and enlightenment to the geek community, I present my list of most common irritating mistakes.
PRINCIPAL and PRINCIPLE: In particular, the person who is in charge of a research grant is the Principal Investigator - the main one, and NOT the Principle Investigator - someone who is investigating principles. I suppose if you are doing the Equivalence Principle experiment you can call yourself the Principle Investigator, but not otherwise.
PUBLICLY not PUBLICALLY (sic): Where did this one come from? I see it everywhere nowadays...
DISCRETE and DISCREET: Integers are discrete. They are rarely discreet.
LOSE and LOOSE: I lose track of how frequently this one is loosed upon the world. Remember that lose (one 'o') means to misplace. Loose (two 'o') means to deliberately let something go free, and is much more rarely used. The headline "Project May Loose (sic) US Involvement" almost certainly meant to say "... May Lose ...".
THE GREENGROCERS' APOSTROPHE: As I walk down the street, I see signs for "colliflower's 1.50/lb" and, in the furniture store window, "cheap mattress's". No genitive is meant here - they mean "cauliflowers" and "mattresses", a simple plural.
ITS and IT'S: The above leads naturally to the distinction between ITS and IT'S. It's very simple to remember that the contraction of "it is" needs its apostrophe, while the possessive word "its" doesn't have one.
SUPERSEDE (not SUPERCEDE). People often mistakenly think this verb is related to CONCEDE and PRECEDE and RECEDE, which derive from Latin CEDERE (to yield). No - it comes from the unrelated SEDERE (to sit), and so is spelt with an S.
E.G. vs. I.E. Another common mistake is to use "i.e." where you really mean "e.g.". If you're giving an example, e.g. "The software package has been improved in several respects, e.g. the documentation is now in English", then use "e.g.". If you're telling the whole story, i.e. you want to say exactly the same thing over but in different words, then use "i.e.".
AFFECT (versus EFFECT): If you effect something, you make it happen entirely, not just affect it a bit.
COMPLEMENTARY (not COMPLIMENTARY): I would like to compliment those writers who understand that good spelling is complementary to interesting content when trying to communicate effectively, and not a complimentary extra.
HERE versus HEAR: to show vocal support for something that you hear said, or that you read here, you should yell out "HEAR, HEAR!" - not "HERE, HERE!".
From a contributor: FOREWORD (not FORWARD) is the thing at the beginning of a book.
From my New York correspondent: A for E or I: these are simple spelling mistakes that could be caught by a spelling checker - EXISTENCE not EXISTANCE; DEPENDENT not DEPENDANT (except as a noun); DEFINITE not DEFINATE; DEDUCTIBLE not DEDUCTABLE.
A friend in England reports "THEY'RE" as a mistake for "THEIR" and "SHOULD OF" as a mistake for "SHOULD HAVE". Another correspondent reports sightings of "THERE" instead of "THEIR". Shudder... fortunately I haven't come across these myself. (Update: a software engineer colleague just wrote to me "WOULD OF HELPED" when he meant "WOULD HAVE HELPED". Aaaaaarggh....)
Another contributor: ORIENTED, not ORIENTATED. "We oriented the spacecraft in the anti-solar direction" (in itself a perversion of the original sense of "orient"!).
I also dislike INSURE for ENSURE (seen on local buses: "To insure driver's safety, stand behind line") although I gather this is considered acceptable variant usage in some places.
SITE (versus SIGHT): At two sites in the past week I've sighted someone citing a "web sight". Aaargh. I suppose it is a consistent back-formation by analogy with "light/lite" and "night/nite"!
PEAK (as a mistake for PEEK): Increasing irritation with seeing "sneak peak" peeking out at me from various corners, peaking with its appearance in a tweet from NASA JWST.
WAIVED vs WAVED: The landing was "waved off" since mission control did not want to "waive" (i.e. "issue a waiver for") the weather restrictions. I just saw "waived off" - aargh.
SHOO-IN, not SHOE-IN: There are no shoes involved in shooing someone in.
New 2019 addition: ALLUDE TO, not ELUDE TO. Aargh.
New 2019 addition: Is that a flash of LIGHTNING I see? No - just the dawn, it is LIGHTENING (getting lighter) in the east.
Ah, at last. Somewhere to vent my frustration - that feels better now. More to be added here each time I get irritated.