The phrase "forward slash" contains a space, while its equivalent "backslash" does not. This seems inconsistent; should "forwardslash" not be a valid word?
From Wikipedia I discovered that slash, rather than being a group term, is actually the correct name for a forward slash; with the forward qualifier simply being added for clarity.
Is there a rule underlying the use of the space in "forward slash" but not in "backslash", or is it just down to typical usage?
Best Answer
Forward slashes have been around forever (well, at least since Ancient Rome), but they were just called "slash".
Backslashes, on the other hand, are a fairly recent invention. How ASCII Got its Backslash reports that it was added to the ASCII character set in 1961 for the Algol programming language. The term rose in popularity in the early 80's, probably tied to the rise of MS-DOS.
Why is it "backslash" and not "backward slash"? Simply because that's what the guy who invented it(*) called it and it stuck. Had he called it "backward slash", it's debatable whether common use would have eventually shortened it to "backslash".
"Forward slash" is used comparatively less often, and only when someone wants to be really specific about which slash to use. I still hear it called just "slash" a lot.
As for the "rule" that governs whether it's written as one word or two? Compound words in English can be written with or without a hyphen or space; it just comes down to common usage. As this article points out:
(*) Technically the backslash existed in some form prior to its inclusion in ASCII, but it was not in widespread use and I could find no evidence of its name prior to that point.