Why You Should Never Hyphenate an ‘-ly’ Word

Compound modifiers add flair to writing. They combine two or more words that act as a single unit to describe or modify a noun, such as an open-minded person or a well-behaved dog. Playwright William Shakespeare coined many clever compound modifiers, including “lily-livered” (cowardly) and “clay-brained” (lacking intelligence).

You might notice that all of these word pairings have one thing in common: hyphens. When two (or more) modifiers are combined with a noun, those modifiers are hyphenated. But one major exception to this rule exists. Don’t hyphenate an adverb when it acts as a compound modifier.

Many common compound modifiers in English are formed by an adverb (usually spotted as a word with an “-ly” ending) paired with an adjective or participle. Words such as “truly,” “madly,” and “deeply” don’t need a hyphen when paired with another modifier to describe a noun. Instead, you would write “a truly amazing book,” “a madly expensive handbag,” or “a deeply felt sentiment.” Adding a hyphen to any of these pairings is redundant because an adverb cannot modify a noun by itself — there is no such thing as a truly book, a madly handbag, or a deeply sentiment.

This rule applies to true adverbs formed from a root word, not every word that happens to end in “-ly.” For example, some words ending in “-ly” are not adverbs but adjectives. When an adjective is the first word of a compound modifier, a hyphen is needed. You could go on an early-morning walk and meet a friendly-looking neighbor who is walking their curly-haired dog. Other “-ly” words are nouns themselves: Think “family-owned business.” 

And then, of course, there are adverbs that don’t end in “-ly,” such as “slow,” “fast,” “bright,” and “dark.” These are known as flat adverbs — they can work as either adjectives or adverbs, but you have to pay attention to whether the word is modifying a noun or a verb. When used in a compound modifier, these flat adverbs are usually hyphenated for clarity. For example, you would hyphenate “fast-moving car” and “slow-paced movie.” One exception to this rule is the adverb “very.” You would not hyphenate “very good time.” 

Just when you thought you had the rules down pat, English throws another wrench into the works. Typically, compound modifiers come before a noun, but on occasion, they come after. If a compound modifier comes after the noun, it usually does not need to be hyphenated, regardless of whether it’s an “-ly” adverb or not. In this sentence structure, the noun is usually followed by a linking verb such as “is” or “are,” and the modifier follows after that.

Here are a few examples:

• The director is newly appointed. 
• That theory is widely accepted.
• The author is well known.
• The goals are long term.

Note: Certain compounds retain their hyphens after a noun, so check your preferred style guide or dictionary when in doubt.

Most compound modifiers — from the everyday “well-known” to the Shakespearean “lily-livered” — require hyphens when they appear before a noun. However, you can skip the hyphen when the modifier uses an “-ly” adverb, as in “newly discovered,” or when the modifier follows the noun, as in, “The author is well known.” As with many English punctuation rules, context and usage matter.