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Introduction to the -ly Suffix
The suffix -ly is the primary means of forming adverbs from adjectives in English. By adding -ly to an adjective, you create a word that describes how an action is performed: "quick" becomes "quickly," "careful" becomes "carefully," "honest" becomes "honestly."
The -ly suffix comes from Old English -lice, which itself derived from lic meaning "body" or "form." Over centuries, this suffix evolved into a marker of manner adverbs. Today, -ly is one of the most recognizable and productive suffixes in English, central to both grammar and spelling.
However, -ly is not as simple as it first appears. Not all -ly words are adverbs (some are adjectives), not all adverbs end in -ly (some are "flat adverbs"), and the spelling rules for adding -ly involve several important patterns and exceptions.
Basic Spelling Rules
Rule 1: Simply Add -ly to Most Adjectives
The default rule is straightforward: add -ly to the adjective without any changes. Quick → quickly, slow → slowly, soft → softly, loud → loudly, bright → brightly, cheap → cheaply, clear → clearly, deep → deeply, fair → fairly, firm → firmly, neat → neatly, proud → proudly, quiet → quietly, smooth → smoothly, sweet → sweetly.
Rule 2: Adjectives Ending in -y → Change Y to I, Add -ly
When an adjective ends in a consonant + y, change the Y to I and add -ly: happy → happily, easy → easily, angry → angrily, busy → busily, heavy → heavily, hungry → hungrily, lazy → lazily, lucky → luckily, noisy → noisily, steady → steadily.
Exception: shy → shyly (not "shily"), sly → slyly, dry → dryly (or drily—both are accepted).
Rule 3: Adjectives Ending in -le → Change -le to -ly
When an adjective ends in a consonant + le, drop the -e and add -y (effectively changing -le to -ly): simple → simply, gentle → gently, humble → humbly, possible → possibly, probable → probably, comfortable → comfortably, terrible → terribly, horrible → horribly, incredible → incredibly, reasonable → reasonably, subtle → subtly.
Rule 4: Adjectives Ending in -ic → Add -ally
When an adjective ends in -ic, add -ally (not just -ly): basic → basically, dramatic → dramatically, automatic → automatically, enthusiastic → enthusiastically, romantic → romantically, scientific → scientifically, specific → specifically, systematic → systematically, tragic → tragically.
Major exception: public → publicly (not "publically," though this variant is sometimes seen).
Rule 5: Adjectives Ending in -ll → Add -y Only
When an adjective already ends in -ll, just add -y: full → fully, dull → dully, shrill → shrilly.
Rule 6: Adjectives Ending in -ue → Drop -e, Add -ly
True → truly, due → duly. These are the only common examples of this pattern.
Special Spelling Cases
Adjectives Ending in -e (other than -le and -ue)
Most adjectives ending in -e simply add -ly: sincere → sincerely, severe → severely, polite → politely, complete → completely, extreme → extremely, immense → immensely, intense → intensely, precise → precisely, safe → safely, rare → rarely.
Exception: whole → wholly (the -e is dropped).
Adjectives Ending in -l
When an adjective ends in a single -l, add -ly (creating a double-l): beautiful → beautifully, careful → carefully, cheerful → cheerfully, faithful → faithfully, graceful → gracefully, hopeful → hopefully, peaceful → peacefully, powerful → powerfully, successful → successfully, wonderful → wonderfully.
Adjective-Adverb Pairs
Understanding the relationship between adjectives and their -ly adverb forms strengthens your grasp of sentence structure.
- Adjective (modifies nouns): "She gave a careful answer." / Adverb (modifies verbs): "She answered carefully."
- Adjective: "He is a slow walker." / Adverb: "He walks slowly."
- Adjective: "That was a beautiful performance." / Adverb: "She performed beautifully."
The adverb answers the question "how?"—how did she answer? carefully. How does he walk? slowly. How did she perform? beautifully.
Words Ending in -ly That Are Adjectives
Not all -ly words are adverbs. Many common adjectives end in -ly, which can cause confusion:
Friendly, lovely, lonely, lively, costly, cowardly, deadly, elderly, ghostly, godly, homely, likely, manly, orderly, scholarly, silly, timely, ugly, unruly, weekly, worldly.
These are adjectives, not adverbs. You cannot say "she spoke friendly." Instead, use a phrase: "She spoke in a friendly manner" or "She spoke in a friendly way." Some style guides accept constructions like "She smiled friendly" in informal speech, but in formal writing, the prepositional phrase is preferred.
To make adverbs from these -ly adjectives, you typically need a phrase: "in a friendly way," "in a lively manner," "at a costly rate." Adding -ly again (*friendlily, *lovelily) sounds awkward and is generally avoided.
Flat Adverbs: Adverbs Without -ly
Some words function as adverbs without the -ly ending—these are called "flat adverbs." They have the same form as their adjective counterparts:
- Fast: "He is a fast runner" (adjective) / "He runs fast" (adverb). Not "fastly."
- Hard: "It was hard work" (adjective) / "She works hard" (adverb). Note: "hardly" exists but means "barely," not "in a hard manner."
- Late: "A late arrival" (adjective) / "She arrived late" (adverb). "Lately" exists but means "recently."
- Near: "The near future" (adjective) / "Come near" (adverb). "Nearly" means "almost."
- Straight: "A straight line" / "Go straight ahead."
- Wrong: "The wrong answer" / "You guessed wrong." ("Wrongly" also exists and is used in formal contexts.)
- Right: "The right direction" / "Turn right."
- High: "A high mountain" / "Aim high." ("Highly" means "very much.")
Flat adverbs were more common in older English. Over time, the -ly forms have increasingly dominated, and using some flat adverbs (like "He drove slow") is sometimes considered informal. Both "Drive slow" and "Drive slowly" are widely accepted.
Common -ly Adverbs by Function
Manner (How?)
Quickly, slowly, carefully, quietly, loudly, gently, roughly, smoothly, softly, firmly, gracefully, awkwardly, badly, beautifully, brilliantly, calmly, clearly, elegantly, fiercely, freely, honestly, patiently.
Frequency (How often?)
Frequently, rarely, occasionally, regularly, usually, normally, commonly, repeatedly, constantly, continually, periodically, routinely, seldomly (rare—"seldom" is standard).
Degree (To what extent?)
Absolutely, barely, completely, entirely, extremely, fairly, greatly, hardly, highly, largely, merely, mostly, nearly, partly, perfectly, purely, really, slightly, thoroughly, totally, utterly, vastly, wholly.
Time (When?)
Currently, eventually, finally, formerly, immediately, lately, presently, previously, recently, simultaneously, subsequently, ultimately.
Sentence Adverbs
Some -ly adverbs modify entire sentences rather than specific verbs: "Fortunately, no one was hurt." "Apparently, the meeting has been canceled." "Interestingly, the results contradicted the hypothesis." Other common sentence adverbs: admittedly, arguably, certainly, clearly, evidently, hopefully, importantly, naturally, obviously, presumably, surprisingly, undoubtedly.
Avoiding Overuse in Writing
While -ly adverbs are useful, overusing them can weaken your writing. Many writing guides advise cutting unnecessary adverbs, especially in creative writing.
Why? Adverbs often prop up weak verbs. "She walked quickly" is less vivid than "She hurried" or "She strode" or "She sprinted." Replacing the verb-adverb combination with a single, precise verb creates stronger, more engaging prose.
Dialogue tags are another common area of adverb overuse. "'I'm fine,' she said angrily" tells the reader about the emotion rather than showing it. "'I'm fine,' she snapped" lets the verb do the work.
This does not mean you should eliminate all adverbs—that would be equally misguided. When an adverb genuinely adds information that the verb alone cannot convey, use it. "He closed the door quietly" tells us something different from "He closed the door." The key is to use adverbs deliberately rather than habitually.
-ly Adverbs and Hyphens
An important punctuation rule: do not hyphenate compound modifiers when the first word is an -ly adverb. Write "a carefully written report" (no hyphen), not "a carefully-written report." However, non-ly adverbs in compound modifiers do take a hyphen: "a well-written report," "a fast-moving vehicle."
This rule applies because -ly clearly signals that the word is an adverb modifying the adjective that follows, so no hyphen is needed for clarity.
Practice Exercises
- Form the adverb: comfortable → comfortably, dramatic → dramatically, true → truly, happy → happily, gentle → gently, full → fully, public → publicly, whole → wholly.
- Identify the error: "She drove careful through the rain." (Should be "carefully.") "He spoke very friendly." (Should be "in a friendly manner" or "in a friendly way.")
- Replace with a stronger verb: "She walked quickly" → "She hurried." "He said loudly" → "He shouted." "She smiled happily" → "She beamed."
Conclusion
The -ly suffix is the backbone of English adverb formation. By mastering its spelling rules—the Y-to-I change, the -le to -ly pattern, the -ic to -ically rule—and understanding the exceptions, you gain reliable tools for both spelling and grammar. Equally important is knowing when -ly adverbs serve your writing and when stronger verbs or other constructions would be more effective. A confident command of -ly words makes your writing both grammatically sound and stylistically polished.