“Catalogue” can also be spelled “catalog.” “Dialogue” can also be spelled “dialog.” But “monologue” is rarely spelled “monolog.”
The Americans are at it again.
The combining form “logue” is French, descended from Latin, and it indicates an engagement of some sort, a discourse, if you will, between people or things. People browse “catalog(ue)s” to “discuss” what items to buy; a “dialog(ue)” is a conversation between two people; a “monologue” is a discourse between a person and some thoughts. An “epilog(ue)” is the closing part of a piece of writing, usually to wrap up some loose ends, and so on.
English (as in British) dictionaries will list the “ue” endings as preferred, if they list the shortened versions at all, which many do not. When they do, they are usually labeled “chiefly American” or something similar. American-based dictionaries often acknowledge the British usage, but the “ue” form might be listed as a secondary spelling or as a “variant,” meaning “deviation from the standard form.” That’s a step or two less desirable than being an alternate spelling. (Beware, though, that some spelling checkers will accept both forms.)
For example, the American Heritage, Webster’s New World College, and Merriam-Webster dictionaries, all red-blooded American reference works, agree that “dialog” is preferred, as do the New York Times, Associated Press, and Chicago style manuals.
But for “monologue,” dictionaries list it at best as a variant, never just as an alternate spelling. Some other words are in the “monologue” category: Almost no one spells “ideologue” without its “ue,” and “prologue” appears without “ue” only in the name of a computer program.
Why do some words get to drop the “ue” but others can’t, at least not yet?
Because Americans said so, that’s why.
Call it laziness, call it thrift (those “ue’s” don’t grow on trees, you know), call it personalization, but it may have as much to do with familiarization with the word as any nefarious plot against the British. The more a word is used, perhaps, the more people might be tempted to shorten it a bit.
Some words have made the full transition to “American.” “Analog” is rarely spelled as “analogue” any more, even in England, largely because of computers. And of course, some words show no signs of dropping their “ue” endings: “brogue,” “tongue,” “vogue,” etc., whose endings are part of a different combining form.
There is at least one place where American tastes and English have coincided. The “chaise longue,” or “long chair,” has been so spelled for more than 200 years. (Well, sometimes it has a hyphen.) But it’s also been spelled “chaise lounge” for nearly as long. It probably has something to do with the extreme similarity in spelling, and the default to a familiar word. Even though some rail that one should never combine a French word (“chaise”) and an English one (“lounge”), many dictionaries list them as equals. And the Associated Press prefers “chaise lounge.”
Now you can lie back and read that nice “travelog(ue).”