Lew Rockwell links to the solecism section of the Economist's style guide.
Here's a digest for those with busy schedules or short attention spans:
Acronym: this is a word, like radar or NATO, not a set of initials, like the BBC or the IMF.
Aggression is an unattractive quality, so do not call a keen salesman an aggressive one (unless his foot is in the door or beyond).
Agree: things are agreed on, to or about, not just agreed.
Aggravate means make worse, not irritate or annoy.
Anarchy means the complete absence of law or government. It may be harmonious or chaotic. [Thank you!]
Autarchy means absolute sovereignty. Autarky means self-sufficiency.
Beg the question means neither raise the question, invite the question nor evade the answer. To beg the question is to adopt an argument whose conclusion depends upon assuming the truth of the very conclusion the argument is designed to produce. All governments should promote free trade because otherwise protectionism will increase. This begs the question.
Bellwether. This is the leading sheep of a flock, on whose neck a bell is hung. It is nothing to do with climate, prevailing winds or the like.
Canute's exercise on the seashore was designed to persuade his courtiers of what he knew to be true but they doubted, ie, that he was not omnipotent. Don't imply he was surprised to get his feet wet.
Cartel. A cartel is a group that restricts supply in order to drive up prices. Do not use it to describe any old syndicate or association of producers — especially of drugs.
Cassandra's predictions were correct but not believed.
Catalyst: this is something that speeds up a chemical reaction while itself remaining unchanged. Do not confuse it with one of the agents.
Centred on, not around or in.
Compare: A is compared with B when you draw attention to the difference. A is compared to B only when you want to stress their similarity. ("Shall I compare thee to a summer's day?")
Contemporary: see Current.
Continuous describes something uninterrupted. Continual admits of a break. If your neighbours play loud music every night, it is a continual nuisance; it is not a continuous one unless the music is never turned off.
Convince. Don't convince people to do something. In that context the word you want is persuade. The prime minister was persuaded to call a June election; he was convinced of the wisdom of doing so only after he had won.
Current and contemporary mean at that time, not necessarily at this time. So a series of current prices from 1960 to 1970 will not be in today's prices, just as contemporary art in 1800 was not modern art. Contemporary history is a contradiction in terms.
Deal. Transitively, this means distribute: "He was dealt two aces, two kings and a six." Intransitively, deal means engage in business. Do not deal horses, weapons, drugs, etc; deal in them.
Decimate means to destroy a proportion (originally a tenth) of a group of people or things, not to destroy them all or nearly all.
Different from, not to or than.
Dilemma. This is not just any old awkwardness, it is one with horns, being, properly, a form of argument (the horned syllogism) in which you find yourself committed to accept one of two propositions each of which contradicts your original contention. Thus a dilemma offers the choice between two alternatives, each with equally nasty consequences.
Discreet means circumspect or prudent; discrete means separate or distinct. Remember that "Questions are never indiscreet. Answers sometimes are." (Oscar Wilde)
Disinterested means impartial; uninterested means bored. ("Disinterested curiosity is the lifeblood of civilisation." – G.M. Trevelyan)
Enormity means a crime, sin or monstrous wickedness. It does not mean immensity.
Epicentre means that point on the earth's surface above the centre of an earthquake. To say that Mr Putin was at the epicentre of the dispute suggests that the argument took place underground.
Ex- (and former): be careful. A Communist ex-member has lost his seat; an ex-Communist member has lost his party.
Factoid: something that sounds like a fact, is thought by many to be a fact (perhaps because it is repeated so often), but is not in fact a fact.
Fewer (not less) than seven speeches, fewer than seven samurai. Use fewer, not less, with numbers of individual items or people. Less than £200, less than 700 tonnes of oil, less than a third, because these are measured quantities or proportions, not individual items.
Flaunt means display; flout means disdain. If you flout this distinction, you will flaunt your ignorance.
Forgo means do without; it forgoes the e. Forego means go before. A foregone conclusion is one that is predetermined; a forgone conclusion is non-existent.
Former: see Ex-.
Frankenstein was not a monster, but its creator. [As a wise-ass kid in grammar school, I liked to make fun of the kids who thought Frankenstein was the monster, but now I think this point is as silly as correcting someone who claims to drive a Ford ("Ford was the creator, you know, not the pickup truck!")]
Gender is a word to be applied to grammar, not people. If someone is female, that is her sex, not her gender. (The gender of Mädchen, the German word for girl, is neuter, as is Weib, a wife or woman.)
Gourmet means epicure; gourmand means greedy-guts. [This is how the distinction was taught to me by my middle-school French teacher, but I've heard it contradicted in at least 2 different ways by those in the know: (1) A gourmet is a gourmand who knows wines; (2) a gourmand loves food (but is not necessarily overindulgent) whereas a gourmet only likes the very finest foods.]
Homogeneous means of the same kind or nature. Homogenous means similar because of common descent. [I know many economists who get this wrong.]
Homosexual: since this word comes from the Greek word homos (same), not the Latin word homo (man), it applies as much to women as to men. It is therefore as daft to write homosexuals and lesbians as to write people and women.
Hopefully: by all means begin an article hopefully, but never write Hopefully, it will be finished by Wednesday. Try With luck, if all goes well, it is hoped that …
Immolate means to sacrifice, not to burn.
Inchoate means not fully developed or at an early stage, not incoherent or chaotic.
Investigations of, not into.
Like governs nouns and pronouns, not verbs and clauses. So as in America not like in America. But authorities like Fowler and Gowers is a perfectly acceptable alternative to authorities such as Fowler and Gowers.
Masterful means imperious. Masterly means skilled.
Mitigates mollifies; militates does the opposite.
Only. Put only as close as you can to the words it qualifies. Thus, These animals mate only in June. To say They only mate in June implies that in June they do nothing else.
Oxymoron: an oxymoron is not an unintentional contradiction in terms but a figure of speech in which contradictory terms are deliberately combined, as in bitter-sweet, cruel kindness, sweet sorrow, etc.
Populace. This is a term for the common people, not a synonym for the population.
Positive means definitely laid down, beyond possibility of doubt, absolute, fully convinced or greater than zero. It does not mean good. It was a positive meeting probably means It was a good, or fruitful, meeting.
Practicable means feasible. Practical means useful.
Presently means soon, not at present. ("Presently Kep opened the door of the shed, and let out Jemima Puddle-Duck." – Beatrix Potter)
Prevaricate means evade the truth; procrastinate means delay. ("Procrastination — or punctuality, if you are Oscar Wilde — is the thief of time.")
Pristine means original or former; it does not mean clean.
Propaganda (which is singular) means a systematic effort to spread doctrine or opinions. It is not a synonym for lies.
Rebut means repel or meet in argument. Refute, which is stronger, means disprove. Neither should be used as a synonym for deny. ("Shakespeare never has six lines together without a fault. Perhaps you may find seven: but this does not refute my general assertion." – Samuel Johnson)
Sensual means carnal or voluptuous. Sensuous means pertaining to aesthetic appreciation, without any implication of lasciviousness.
Soi-disant means self-styled, not so-called.
Straight means direct or uncurved; strait means narrow or tight. The strait-laced tend to be straight-faced.
To or and? To try and end the killing does not mean the same as to try to end the killing.
Underprivileged. Since a privilege is a special favour or advantage, it is by definition not something to which everyone is entitled. So underprivileged, by implying the right to privileges for all, is not just ugly jargon but also nonsense.
Use and abuse: two words much used and abused. You take drugs, not use them (Does he use sugar?). And drug abuse is just drug taking, as is substance abuse, unless it is glue sniffing or bun throwing.
Verbal: every agreement, except the nod-and-wink variety, is verbal. If you mean one that was not written down, describe it as oral.
Which informs, that defines. This is the house that Jack built. But This house, which Jack built, is now falling down. Americans tend to be fussy about making a distinction between which and that. Good writers of British English are less fastidious. ("We have left undone those things which we ought to have done.")