Many writers wrongly see some pairs of words as synonyms, alternating between them randomly or using one in ways that violate convention or ignore its origins. Reminding me of this was Henry Kissinger’s use of historic in a recent opinion piece in the Washington Post:

Essentially tactical issues have overwhelmed the most important challenge a new administration will confront: how to distill a new international order from three simultaneous revolutions occurring around the globe: (a) the transformation of the traditional state system of Europe; (b) the radical Islamist challenge to historic notions of sovereignty; and (c) the drift of the center of gravity of international affairs from the Atlantic to the Pacific and Indian Oceans.

I won’t comment on the sentence’s length (67 words), on the use of two colons, or on the use of letters (a, b, c) to indicate the three (1, 2, 3) revolutions. I will stick instead to the use of historic. Kissinger may have used historic to avoid repeating traditional.

Historic’s seeming synonym is historical. The difference? Historical is history’s ordinary adjective, meaning of history. Historic means memorable or dramatic, but I don’t believe that Kissinger was thinking of memorable notions or dramatic notions.

Would anybody misread the second revolution? Yes. I would. Does distinguishing the two seeming synonyms make a difference? I believe that it does. So does Fowler in Modern English Usage: “the use of one in a sense now generally expressed by the other is a definite backsliding.”

Historic also means assured of a place in history, as with historic accord or historic building. Grammarians also use historic as a technical term, as with the tense, historic present, the use of the present tense to relate events that occurred in the past..

Here are three other seeming synonyms routinely abused:

Comprise (embrace) and constitute (make up), as in “The whole comprises the parts, and the parts constitute the whole.”

Imply (suggest to the reader or listener) and infer (conclude from the writer or speaker), in “Are you implying that we should act on this? And may we infer from what you say that we should act on this?”

Masterful (domineering) and masterly (skillful), as in The Economist’s take on Saddam Hussein’s gulf war strategy: “more masterful than masterly.” True, some dictionaries have a second definition of masterful that is the same as that for masterly, reflecting the words’ early history as synonyms and the practice of most dictionaries of recording usage rather than pronouncing on proper usage. (I still shudder at the Merriam-Webster New Collegiate Dictionary’s including prioritize as a verb.)

There are countless others. See Edit Yourself and the ClearEdits compare function.

Note

My colleague Meta pointed me to Merriam-Webster, for the definition of masterful:

Some commentators insist that use of masterful should be limited to sense 1 in order to preserve a distinction between it and masterly. The distinction is a modern one, excogitated by a 20th century pundit in disregard of the history of the word. Both words developed in a parallel manner but the earlier sense of masterly, equivalent to masterful 1, dropped out of use. Since masterly had but one sense, the pundit opined that it would be tidy if masterful were likewise limited to one sense and he forthwith condemned use of masterful 2 as an error. Sense 2 of masterful, which is slightly older than the sense of masterly intended to replace it, has continued in reputable use all along; it cannot rationally be called an error.

Samuel Johnson's dictionary gave both meanings for masterly:

1. Suitable to a master; artful; skilful.

2. Imperious; with the sway of a master.

(He did not include masterful.)

And this is what Fowler (the 20^th century pundit?) writes in Modern English Usage for masterful, masterly:

Some centuries ago both were used without distinction in either of two very different senses: (A) imperious or commanding or strong-willed, and (B) skilful or expert or practiced. The differentiation is now complete, -ful having the (A) and -ly the (B) meaning, and is nicely observed in The presentation in each case was masterly (perhaps in a few rare instances a trifle too masterful) and always the playing was crystal clear.

I agree with Fowler (and Meta) that the distinction is useful (I won’t comment on his use of A and B). If someone were to write, Diana Vishneva’s performance was masterful, how would I to know whether it was an expert performance or an imperious performance?

Masterful in the (B) meaning may survive because of the clumsiness of forming an adverb from the adjective masterly: masterlily. Masterfully clearly is less clumsy.