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Common Usage Errors on the Seeking Alpha Site (#2)

(Hat tip for some of the definitions below to R.H. Fiske’s Dictionary of Disagreeable English.)
Aide / Aid
Aide = An assistant (noun);
Aid = To help (verb);
“regulations have been rewritten behind closed doors with the aide aid of Sun Edison”
Alternate / Alternative
Alternate = By turns, back-and-forth (verb or adjective);
Alternative = A choice among two or more things;
“An alternate alternative theory gaining a bit of credibility compared to ‘first a slight correction, then to da moon!’ is that commodities, oil and gold will trade in a wide consolidation pattern”
Between / Among
Between = Best used where only two items are involved;
Among = Best used where three or more items are involved;
“the report included as exhibits several e-mail exchanges between among analysts at unnamed ratings firms”
Bimonthly or Semimonthly / Two-monthly or Twice-monthly
Bimonthly / Semimonthly are hopelessly ambiguous, meaning either twice a month or every other month. Fowler's Modern English Usage therefore recommends using the wordier and more awkward but unambiguous terms “two-monthly” and “half-monthly,” but the latter has an unidiomatic sound in US English—“twice-monthly” is more natural and clearer. (Hmm--maybe "alternate-monthly" would be better than "two-monthly"?)
“Founded as a quarterly journal in 1970, the magazine was relaunched as a glossy bimonthly two-monthly magazine in 2000”
Canvas / Canvass
Canvas = Strong, close-knit cloth;
Canvass = Survey (noun or verb);
“my canvas canvass of the stock tells me that none of the big holders is going to sell that stock.”
Continual / Continuous or Continuing
Continual = Recurring at intervals;
Continuous or Continuing = Without cessation, unending;
“Perhaps the real story is the dollar and until the expectation for a continual continuing decline changes ...”
Criteria / Criterion
Criteria = Standards (plural of criterion);
Criterion = Standard;
“This was done via a number of structures with really only one criteria criterion rated at least AA-”
Disinterest / Indifference
Disinterest = Objectivity, impartiality;
Indifference = Apathy, lack of interest;
“There is no legal structure that can survive the disinterest indifference of those charged with upholding it.”
Insure / Ensure / Assure
Insure = To provide monetary protection against a loss;
Ensure = To make certain; 
Assure = To promise;
“Once you have established a reliable energy grid you need to insure ensure real-time fault tolerant communications, …”
“For those on the inside, who may cooperate to insure ensure that they know tomorrow's news, today, it would be a money machine”
Extant / Extent
Extant = Still in existence;
Extent = Range, scope;
“And to the extant extent that there's a death rattle, the values are roughly half ….”
Farther / Further
Farther = Physical distance;
Further = Abstract distance;
“They could take it much farther further than this, …”
Flaunt / Flout
Flaunt = To show off;
Flout = To contemptuously disobey;
“Bond traders flaunt flout inflation.”
Hairbrained / Harebrained
Hairbrained = (no such word);
Harebrained = Scatterbrained;
“Microsoft should stop these hairbrained harebrained schemes”
Hung / Hanged
Hung = (applies today only to objects like pictures);
Hanged = Executed;
“And I for one would love to see the group as a whole be hung hanged publicly”
I.e., / E.g., 
I.e., = That is; In other words;
E.g., = For example; By way of illustration;
“Dont confuse where you buy stuff, i.e., e.g., wallmart, with where you make stuff, i.e., e.g., China.”
“Many politicians end up working for defense contractors (i.e., e.g., Dick Cheney)”
Note: This is a very common error. An associated error is omitting the commas that should precede and follow the term, or the two periods within it.
Lead / Led
Lead = To guide, precede—not a past tense;
Led = Past tense of lead;
“the Asian economies in 1998 experienced tremendous Deflation (Debt Deflation), which lead led to MASSIVE Inflation.”
Loose / Lose
Loose = Not fastened, not tight;
Lose = To misplace something, or to have it diminished;
“You can loose lose as much as you put in plus more”
“The notion that more lose loose credit can fix the ravages of lose loose credit has temporarily intoxicated the market”
Negative Feedback Loop / Positive Feedback Loop
Negative feedback loop = “Dampening” feedback;
Positive feedback loop = “Amplifying” feedback;
Wikipedia writes: “feeding back part of the output so as to increase the input is positive feedback; feeding back part of the output in such a way as to partially oppose the input is negative feedback. … Negative feedback helps to maintain stability in a system in spite of external changes. … For example, in a population of foxes (predators) and rabbits (prey), an increase in the number of foxes will cause a reduction in the number of rabbits; the smaller rabbit population will sustain fewer foxes, and the fox population will fall back. … Positive feedback amplifies possibilities of divergences …“
IOW, positive (self-reinforcing) feedback loops are what are involved in such “negative” phenomena as “death spirals,” “races to the bottom,” beggar-thy-neighbor policies,” “arms races,” “tipping points,” “escalation,” etc. But since “negative” has a connotation of “bad,” it is very common to see amplifying (positive) feedback loops incorrectly described as “negative,” thus:
“Concern about unemployment itself becomes a circular reinforcing factor, or ‘negative positive feedback loop.’”
Past / Passed
Past = Prior time--not a verb—mostly a noun or adjective;
Passed = Past tense of the verb “to pass”;
“… more stable periods in market and economy in times passed past …”
Penultimate / Last
Penultimate = Next-to-last item;
Last = Final item;
“Aug 28, 2009 ... I expect a very boring session [today] as many remain on vacation and it is the penultimate last Friday of the summer.”
Note: Penultimate is often used by copy-editors when referring to a line on a page or in a paragraph. They also use the word antepenultimate, meaning two-before-the-last.
Phase / Faze
Phase = A period of time;
Faze = To disconcert;
“Lloyds fell 5% in London trading, but analysts were unphased unfazed.
Rational / Rationale
Rational = Logical (adverb);
Rationale = A reasonable justification for an action or position (noun);
“I want to today provide you with a summary of the GMAC RE business and the rational rationale that supports Maiden's acquisition …”
Refer / Allude
Refer = To mention by citing someone or something;
Allude = To mention indirectly, without naming—a vague reference;
“What you refer allude to seems to me to be the realization that social mood is the driver for activities”
“Yes; ‘variance’ in this context was used generically and was not meant to allude refer to the statistical metric.”
Refute / Rebut
Refute = To disprove;
Rebut = To reply with a counter-argument;
“To add insult to injury, Mises wasn't even refuted rebutted by Keynes and his ilk. He was ignored.”
“Greater Depression for U.S. Rebuts Refutes 'Recovery' Talk.”
Reign / Rein
Reign = rule, sovereignty;
Rein = a means of restraint;
“the U.S. government has no stomach for reigning reining in budget deficits”
Shibboleth / Platitude
Shibboleth = A “U-word” (Nancy Mitford) or catchphrase of some specific in-group or clique—often a bit of “insider” jargon;
Platitude  = A commonplace saying or truism;
“the oft-repeated shibboleth platitude that we ‘need’ baseload generation ….”
Straight / Strait
Straight = Lacking curves, direct;
Strait = Narrow (adverb); a narrow waterway (noun) -- figuratively, “tight” or “a tight spot”);
“The US is in dire straights straits no doubt”
“union seniority puts them in a straight strait jacket”
(BTW: “strait-laced” is correct; the much more common “straight-laced” is meaningless.)
Verbal / Oral
Verbal = By word, either spoken or written;
Oral = Spoken only;
“Now, when I meet those people, I can provide a verbal an oral explanation ….”
Who’s / Whose
Who’s = Contraction of who is;
Whose = Belonging to the person or object referred to;
“But for a small time trader who's whose trading doesn't affect the market, …”
Your / You’re
Your = Belonging to you;
You’re = Contraction of you are;
“If your you’re a trend trader, ….” 

Second Group – Matters of Taste:

 / A
An = Used in before a word that lacks an initial consonant, or whose initial consonant is not pronounced;
A = Used before words that are pronounced with an initial consonant;
“If you have access to an historical chart of gold prices”
But: “an herb” (because the “h” in “herb” is silent)
Note: This is not a black-and-white matter. In British English, and in old-fashioned American English, it is/was OK to use an “an” before certain h-words—and there is a subtle case for continuing to do so, if you feel strongly about the matter (see link). If you don’t, “a” is preferable. grammartips.homestead....

/ Enormous extent
Enormity = Monstrous wickedness;
Enormous extent = vast extent, vastness, great size;
“we simply cannot appreciate the enormity enormous extent of our current predicaments.”
Note: There are no smooth one-word replacements for “enormity,” which makes things awkard. As a result, writers often use “enormity” because it is handier; and so there is a case for using the word. Here's what Fowler’s Modern English Usage says on this topic: "the use of the first ["enormous"] lays one open to suspicion of pedantry, and of the second ["enormity"] to suspicion of ignorance. 'Enormousness' is not a pretty word, but the writer could have found a way out by writing 'vastness' or 'enormous extent.'"

 / That
Which = The lead-in to a non-defining or parenthetical clause (one preceded by a comma);
That = The preferable lead-in to a defining or ‘restrictive” clause (one not preceded by a comma);
“… it left only four companies which that have grown organically …”
Note: It’s not actually an error to use “which” in both senses.