Slow vs. Slowly – Which is Correct?

Both “slow” and “slowly” are correct, but they serve different grammatical roles. “Slow” can be an adjective describing a person or thing and an adverb in informal usage. “Slowly” is the standard adverb for describing how an action happens. Choose based on whether you need description or manner in context.

This distinction also resembles Different vs. Differently, where adjective and adverb roles determine the correct choice.

Slow or Slowly – Which is Correct?

Slow and slowly are both correct American English words, but they are not always interchangeable. Slow is primarily an adjective: it describes a noun, as in “a slow train.” It can also function as an adverb, especially in informal speech and in phrases such as “drive slow” or “take it slow.”

Slowly is an adverb formed from the adjective slow. It modifies a verb and explains how an action occurs: “The train moved slowly.” In formal or carefully edited writing, slowly is generally the safest choice when modifying an action.

The Best Trick to Remember the Difference

Use the noun test: if the word describes a person, place, thing, or idea, choose slow. Use the action test: if the word explains how someone does something, choose slowly. For example, “a slow runner” describes the runner, while “the runner moved slowly” describes the movement.

How to Use Slow

Slow is most commonly an adjective that describes something operating, moving, or developing at a low speed. It can describe people, machines, transportation, processes, communication, and progress. The word is neutral in tone, although it may sound critical when used to describe a person’s intelligence or performance.

Slow is also used as an adverb in informal English, especially after verbs such as go, drive, run, and take. This use is common in conversation, signs, slogans, and fixed expressions. In formal writing, slowly is often preferred when the word directly modifies an action.

Example 1: The company made slow progress during the first quarter.

Example 2: That is a slow computer, but it still works well.

Example 3: Please drive slow through the school zone. In formal editing, “Please drive slowly” may be preferred.

What are the different forms of slow?

As an adjective, slow has the comparative form slower and the superlative form slowest. For example, “This route is slower than the highway” and “That was the slowest bus in the fleet.” As an adverb, slow can also form slower and slowest, particularly in informal usage: “The engine is running slower today.”

Etymology of the word slow

Slow comes from the Old English word slāw, meaning slow, sluggish, or inactive. It is related to words in other Germanic languages, including Middle Dutch and Old Norse terms associated with slowness or dullness. Its core meaning has remained remarkably consistent over time.

How to Use Slowly

Slowly is an adverb of manner. It modifies a verb by showing that an action happens at a low speed or gradually. It can appear before a verb, after a verb, or at the end of a sentence: “She slowly opened the door,” “The water slowly rose,” or “The audience left slowly.”

Slowly is usually the preferred choice in formal, academic, professional, and carefully edited writing when describing the manner of an action. It can also express gradual change, as in “The market slowly recovered.”

Example 1: The child slowly climbed the stairs.

Example 2: The flowers slowly opened in the morning sunlight.

Example 3: The new policy slowly changed the organization’s approach.

What are the different forms of slowly?

Slowly is an adverb and does not have plural or verb-tense forms. When comparison is necessary, use more slowly and most slowly: “The second vehicle moved more slowly,” and “The damaged vehicle moved the most slowly.” In some contexts, slower and slowest are also used adverbially, but more slowly and most slowly are especially clear in formal writing.

Etymology of the word slowly

Slowly developed by adding the Old English adverbial ending related to modern -ly to slow. The suffix -ly originally carried the sense of “in the manner of” or “in a way that is like.” Therefore, slowly literally means “in a slow manner.”

Related Concepts

Understanding the difference between adjectives and adverbs makes it easier to choose between slow and slowly.

• Adjectives: Adjectives modify nouns or pronouns. In “a slow train,” the adjective slow describes the train.
• Adverbs: Adverbs can modify verbs, adjectives, or other adverbs. In “the train moved slowly,” slowly explains how the train moved.
• Flat adverbs: A flat adverb has the same form as its related adjective. In informal English, slow can act as a flat adverb in “drive slow.”
• Comparative forms: Slower compares two people or things, while slowest identifies the one with the lowest speed among three or more.

Examples from Media and Literature

Both forms appear frequently in titles, dialogue, narration, advertising, and everyday reporting.

• The Tortoise and the Hare: The tortoise is traditionally described as slow, emphasizing a lasting characteristic.
• Take It Slow: This expression uses slow in a familiar informal phrase meaning to proceed without rushing.
• Literary narration: A writer might state, “The door slowly opened,” using slowly to describe the manner of the action.
• News reporting: A report may say, “The economy slowly recovered,” using slowly to describe gradual change.
• Road signs and instructions: Signs may use “Slow” as a concise command telling drivers to reduce their speed.

Practice Exercises

Choose the correct word to complete each sentence.

1. The old printer is very ______.
2. The turtle moved ______ across the garden.
3. Please read the instructions ______.
4. We took a ______ route through the countryside.
5. The patient’s condition ______ improved after treatment.

Answer Key

1. slow — It describes the printer.
2. slowly — It describes how the turtle moved.
3. slowly — It describes how the instructions should be read.
4. slow — It describes the route.
5. slowly — It describes how the condition improved.

Slow Synonyms

Slowly Synonyms

Frequently Asked Questions

Question 1: Is “slowly” more grammatically correct than “slow”?
Not always. Slow is the standard adjective, while slowly is the standard adverb. However, slow is also accepted as an adverb in informal English and in established expressions such as “drive slow” and “take it slow.”

Question 2: Should I write “drive slow” or “drive slowly”?
Both forms are used, but “drive slowly” is usually the better choice in formal or professional writing. “Drive slow” is common in conversation, signs, advertising, and informal instructions.

Question 3: Is it correct to say “slowly but surely”?
Yes. “Slowly but surely” is a standard idiomatic expression meaning that progress is being made gradually and reliably, even if it is not happening quickly.

Question 4: Can “slow” describe a person?
Yes, but context matters. “A slow runner” usually refers to speed, while “a slow learner” may refer to the pace of learning and can sound insensitive depending on the situation. More precise wording is often preferable.

Conclusion

Slow and slowly are both correct. Use slow mainly as an adjective to describe a noun, and use slowly as the standard adverb to explain how an action occurs. Although “slow” works as an informal adverb, choosing “slowly” in formal writing demonstrates grammatical precision and protects your professional reputation.