Nuts & Bolts
Public Relations

Hyphens, En Dashes and Em Dashes

By Tom Milani, WIW Member

When Lewis Thomas wrote in The Medusa and the Snail, "The dash is a handy device, informal and essentially playful, telling you that you're about to take off on a different tack but still in some way connected with the present course," he was referring to the em dash, the punctuation mark formed on the typewriter by typing two hyphens. The em dash is similar to the hyphen and en dash in that it links letters, words or numbers. However, these three punctuation marks each have distinct functions.

The hyphen, smallest of the three, joins elements of words that must remain connected and yet, for various reasons, cannot be further coupled. In "electro-optics" the hyphen prevents the unseemly doubling of Os-electrooptics—which would distort pronunciation and possibly meaning. Consider another example: "pro-Cuban." Here, the hyphen prevents a capital letter appearing within the body of a word-proCuban. For now, that's jarring to the eye, but a trend toward commingling upper- and lower-case letters in computer-related products may change this. Names like WordPerfect and iMac have altered what we're used to seeing, and such constructions may become so common that we won't even notice the unhyphenated compounds. Finally, hyphens also form temporary compounds—words that otherwise would stand apart but are joined to function as unit modifiers. For example, "high-pressure system."

Slightly wider than the hyphen, and of more specific function, is the en dash. Roughly the width of the letter "n" (hence its name), the en dash joins capital letters (AFL-CIO), numbers and capital letters (4-H), and a range of numbers (pp. 47-51). It can also serve as a minus sign, if that particular character, which is raised slightly and of different weight, isn't available.

Twice as wide as the en dash, the em dash also joins and interjects. Unlike parentheses, which contain information that is usually ancillary in nature (an example, an aside), the em dash is meant to be noticed—the information that follows is important-and acts as a bridge within, or to the end of, a sentence.

This article originally appeared in the March 2000 issue of The Independent Writer.