A hyphenated compound is made from two words in English combined by a hyphen. The two words are often adjectives or nouns, and can be used by themselves, but combined with a hyphen they represent a different thing. Common examples are “part-time,” “high-speed,” and “editor-in-chief.” Because English is not completely consistent, and because the written language changes, the use of a hyphenated compound is not always regulated.
The hyphenated compound is generally the least used form of compound word. Often words will begin as an open compound, progress into a hyphenated compound, and with frequent use in the English language, are combined in the common lexicon as one word. An example is the combination of the two words “key” and “board” used separately to describe a computer tool in the early days of its use. They are then combined after some usage into a hyphenated compound: “key-board.” Often, when this usage becomes common, the hyphen gradually gets dropped and the term becomes a one-word compound: “keyboard.”
Modifying and descriptive pronouns often use a hyphenated compound to avoid confusion. Descriptive words like big-time, yellowish-green, and high-rise are combined to make sentences more clear and to combine two unrelated words into one idea. A term like “high-danger situation,” without a hyphenated compound could create confusion. The term obviously refers to a situation with imminent danger. Without the hyphen it would read “high danger situation,” and could describe the same as the hyphenated situation, or it could describe a “high” situation (as in elevated), with a threat of danger (not necessarily “high”). This new construction alters the meaning completely.
Also, English terms with words in the middle or more than two words are usually hyphenated, such as merry-go-round, father-in-law, or ten-year-old. In cases like these, most of the time the term is made plural by adding an “s” to the last of the set of words. In some unusual cases, though, the term is made plural by adding an “s” to the first word, usually the noun, such as “attorneys-at-law.”
Many words began as one type of compound in England under the Germanic languages, but changed to another type of compound after the altering of the language in 1066 with the Norman invasion. Some words have just been changed throughout time because of awkward spelling or usage, and some words, like the original title of Herman Melville’s “Moby-Dick,” were just dropped because they made more sense or seemed more natural without a hyphenated compound.