When to use more slowly instead of slower: a quick grammar guide for action adverbs

Let me ask you something simple: when you’re describing speed, do you use slower or more slowly? It’s a tiny grammar clash that trips up a lot of writers. The way you choose between these two isn’t just a matter of style—it changes what your sentence says. And yes, you’ll find this little nuance pop up in the English section of many language assessments, including the one you’re checking out. So, let’s break it down in plain terms, with a few clear examples you can actually use in everyday writing.

Adjectives vs. adverbs: what’s the difference, really?

Here's the thing: slow is an adjective. It describes a noun. When you say something is slow, you’re saying something about that thing itself. If you say a machine is slow, you’re labeling the machine's inherent speed.

Slowly, on the other hand, is an adverb. It describes how an action happens. When you tell someone how an action is performed—how someone runs, speaks, or moves—you’re using an adverb. So slowly modifies the verb.

Now, what about “more slowly” versus “slower”? That’s where the rules get a tad fussy.

Two quick rules to keep in mind

• If you’re describing an action, and you want to say the action is performed in a slower manner, you usually use more slowly. Example: She runs more slowly than her sister. Here, the word more slowly is formed from the adverb slowly (which itself ends in -ly), and the two-syllable adverb takes the “more” form to show the comparative.

• If you’re comparing the speeds of two things (objects or subjects), you typically use the adjective slower. Example: Machine A is slower than Machine B. In this sentence, slower is a comparative adjective that modifies the noun (machine).

Putting it into simple sentences

• Action-focused: She moves more slowly when she’s tired. (Describing how the action is done.)

• Object-focused: The bike is slower than the car. (Describing the speed of the object itself.)

• Direct contrast that centers on the manner: The narrator speaks more slowly in quiet scenes than in loud, crowded ones. (Describing how the speaking happens.)

Why this distinction matters in real life

Think about emails, essays, or quick notes you jot down. If you want to be precise about how someone does something, you’ll often reach for the adverb form. If you want to compare two things head-to-head, you’ll switch to the adjective form. This isn’t just pedantry. It helps readers know what’s being compared and whether you’re talking about the action itself or the thing performing it.

A few common traps (and how to dodge them)

• Confusing the subject with the action. If you say, “The athlete runs slower,” you’re comparing the speeds of athletes (the subjects), not describing how the running happened. If you want to describe the manner, you’d say, “The athlete runs more slowly than yesterday.” That keeps the focus on the action, not a flat comparison of people.

• Overusing adverbs. It’s tempting to pepper writing with adverbs like quickly, gently, or slowly. It’s fine to use them, but the point is clarity. If a sentence is crisper without the adverb, drop it. And when you do need an adverb to convey manner, more slowly is the precise tool for longer adverbial forms.

• Forgetting the syllable rule. The compelling thing about English is that many two-syllable adverbs formed from adjectives use more. However, there are natural exceptions when speed gets expressed with “faster” (especially with one-syllable adjectives). The key is to listen to how native speakers say it and keep the logic in mind: if you’re modifying a verb with a longer adverb, “more” often fits; if you’re making a direct speed comparison of two things, the adjective form tends to win.

How this shows up in everyday writing and in language assessments

If you’re looking to be precise in English, understanding this distinction helps a lot. It makes your comparisons cleaner and your descriptions sharper. In the language portion of assessments, you’ll often be asked to choose the sentence that uses the right form. The correct choice will make clear whether the comparison is about the action (how something is done) or about the object’s speed (how fast it is).

A tiny, practical-discipline moment

Let me explain with a quick mental picture: imagine you’re watching two robots race on a factory floor. If you’re noting the way they run or move, you’d describe the action. If you’re comparing which robot is faster overall, you’d talk about their speeds as adjectives. The language feels different because it’s serving a different purpose in the sentence.

A mini-checklist you can use next time you write

• Am I describing how something is done? If yes, consider “more slowly” for adverbial emphasis.

• Am I comparing the speed of two things? If yes, consider “slower” as the adjective.

• Is the comparison about the manner, not the object itself? Favor the adverb form (more slowly) to highlight the action.

• Does the sentence still feel natural if I switch forms? If not, try rewriting for the intended emphasis.

A tiny practice set (without turning into a cram session)

• The comedian spoke more slowly during the second set. Why? It focuses on the manner of speaking.

• The river boat is slower than the speedboat. What’s being compared? The ships’ speeds, i.e., the characteristics of the objects.

• She handles the keyboard more slowly after the long shift. What’s the emphasis? The way the action is performed.

• The printer is slower than the scanner. Which is being described? The machine’s speed as a feature of the object.

Shaping clearer communication in everyday life

Beyond tests and quizzes, this nuance helps in emails, reports, and even casual conversations. If you want your message to feel smooth and precise, pay attention to whether you’re weighing the action or the object. A tiny tweak from slower to more slowly or the other way around can shift the focus from what something is to how something is done.

Finding a balance between precision and flow

No one wants sentences to feel robotic or overly stiff. The art of good writing is a balance: be accurate about what you’re describing, but also let the prose breathe. If you’re narrating a scene or telling a story, sometimes the simplest form—“slower”—fits perfectly, especially when speed is a property of the thing rather than the action. When you want to linger on the manner, a phrase like “more slowly” can give your prose a little extra texture.

A closing thought: why this matters beyond tests

Grammar rules like this aren’t just academic. They shape how readers interpret your ideas. They affect clarity, tone, and even the pace of a piece. When you can switch between describing actions with “more slowly” and comparing speeds with “slower,” you’re wielding two useful tools in one hand. It’s a small skill, but in real writing, small skills compound into big results.

If you’re curious to explore more about how English handles speed, manner, and comparison, you’ll find plenty of real-world examples in everyday writing—from product reviews to travel blogs and workplace reports. The trick is to read with an eye for how authors use adverbs and adjectives to guide the reader’s focus. Soon enough, you’ll notice patterns and start applying them naturally, almost without thinking.

In the end, the choice between more slowly and slower isn’t about following a rigid rule so much as about signaling what you want the reader to notice. Do you want to draw attention to the action itself? Use more slowly. Do you want to compare two speeds of objects? Use slower. It’s a tiny decision with a surprisingly visible payoff—one that can sharpen both your everyday writing and your performance on language assessments, all without losing your natural voice.

If you’d like, we can walk through a few more examples together and tailor them to the kind of writing you do most—emails, essays, or reports. I’ll keep the explanations crisp and anchored in real-world usage, so you can feel confident in your choices whenever English comes up in conversation or on that language section.