Q: Please explain why the word importantly is correct in a phrase like, "More importantly, my client was unable to contact his lawyer."

A: It is correct only because it has become idiomatic. Both English grammar and logic require the adjective important instead, but several years ago some public figure attached an unnecessary ‑ly to important, perhaps by analogy to adverbs like luckily, fortunately; and the phrase more importantly has become so popular that it has attained the status of idiom.

The word idiom is derived from the Greek word idioma, which meant, "a person in a private station, without pro-fessional knowledge: a common man." The English meaning of idiom is, "a word or expression peculiar to a language that cannot be explained from the individual meaning of its components."

Webster's Third's definition of idiom is more technical: "The syntactical, grammatical, or structural form peculiar to a language: the genius, habit, or cast of a language." I prefer the definition in the 1993 Columbia Guide to Standard English: "If a locution is idiomatic, it is standard because we have all agreed it is logical."

The phrase more importantly is similar in that respect to that overused adverb hopefully, which traditionally meant "with hope," as in, "He looked hopefully under the mattress for the money." Now hopefully has become a sentence modifier meaning, "it is to be hoped." ("Hopefully it will rain tomorrow.") It is not uncommon for grammatical errors attain idiomatic status, like the idiomatic "It's only me," Or like for as in, "Tell it like it is."

Q: A friend and I are having an argument. He says "however" should not begin a sentence; it should be attached to the previous sentence by a semi‑colon. He argues for, "I did not want to drive that car; however, it was the only one available." I say that the following is correct: "I did not want to drive that car. However, it was the only one available." Who is right?

A: You both are. Your friend is right that the two sentences could be written as one, with a semi‑colon introducing the second half. You are right that two sentences would also be correct. Unlike most decisions, this one should make both lawyers happy. I know that Attorney Michael W. Rathsack, who sent this question, was pleased. He wrote that my answer awarded him a free lunch.

Mr. Rathsack wrote that he generally prefers short sentences to long ones, which is the reason he chose the second alternative. He calls his preference for short sentences the "See Spot Run" school of writing. His writing style of "short plain sentences" is similar to that espoused by Strunk & White's "little book," The Elements of Style, which is still read and admired by many effective writers today.

An advantage of writing two sentences as one, the second half introduced by a conjunctive adverb like however, is that this indicates a closer relationship between the two parts than separate sentences would. The semi‑colon, plus the conjunctive adverb, provides continuity and transition and also indicates the direction of the continuing discussion. Besides however some other conjunctive adverbs are words like moreover, therefore, consequently, furthermore, and nevertheless.

Standard usage once required that commas follow all the conjunctive ad-verbs, but fewer commas are used now, so add a comma only to indicate that a pause follows the adverb. You would omit the comma if you do not intend the reader to pause after therefore in the statement, "The federal deficit is a factor in the annual budget; therefore the budget committee has been meeting regularly." However, usually you do intend a pause after however, furthermore, and nevertheless.

When however and its ilk occur in the middle of a sentence in constructions like, "The student tickets, however, were completely sold out," they are punctuated as shown. Some grammarians caution that in compound sentences the word but is redundant with these adverbs. (For example avoid, "The door was open; but nevertheless a trespassing charge was brought.")

The word however differs from other conjunctive adverbs in that it can act like an adjective. So omit the comma after however in the following sentence: "However long the debate lasts, I will remain until it ends."