Adjective or Adverb Confusion

An adjective describes a noun; an adverb describes a verb, adjective, or another adverb. The confusion usually happens because many learners assume every describing word needs an "-ly" ending, or because certain very common verbs break the expected pattern.

• She is a careful driver. (adjective describing the noun "driver")
• She drives carefully. (adverb describing the verb "drives")

The Basic Rule

Use an adjective after a noun or after a linking verb (be, seem, become, look, feel, sound, taste, smell) to describe the subject. Use an adverb to describe how an action is performed.

• The soup tastes delicious. (adjective after linking verb "tastes")
• He cooked the soup carefully. (adverb describing the action "cooked")
• She looks happy today. (adjective — describes how she appears)
• She smiled happily. (adverb — describes how she smiled)

Good vs Well

Good is an adjective and describes a noun. Well is usually an adverb, describing how an action is performed — except when well means "in good health", in which case it functions as an adjective.

• He's a good singer. (adjective describing "singer")
• He sings well. (adverb describing "sings")
• I don't feel well today. (well = healthy, functioning as an adjective here)

Wrong: He sings good. — "good" cannot describe the verb "sings"; it must be "well".

Tricky Words That Look the Same as Adjectives and Adverbs

Some words, like fast, hard, and late, keep the same form as both an adjective and an adverb.

• He's a fast runner. (adjective) / He runs fast. (adverb — not "fastly")
• It was a hard exam. (adjective) / She studied hard. (adverb — not "hardly", which means something different)
• The train was late. (adjective) / She arrived late. (adverb)

Be careful: hardly is a real word, but it means "almost not", a completely different meaning from "hard" used as an adverb of manner.

• She hardly studied at all. (= she studied very little)
• She studied hard. (= she studied with a lot of effort)

Linking Verbs vs Action Verbs With the Same Word

Some verbs, like look, feel, and smell, can function as either a linking verb (describing the subject, needs adjective) or an action verb (describing how something is done, needs adverb), depending on the meaning.

• She looked nervous. (linking verb: how she appeared → adjective)
• She looked nervously around the room. (action verb: how she performed the looking → adverb)

Common Mistakes

• Using good instead of well with action verbs:
  Wrong: She did really good on the test.
  Correct: She did really well on the test.
• Adding "-ly" to words that don't need it:
  Wrong: He runs fastly.
  Correct: He runs fast.
• Confusing hard and hardly:
  Wrong meaning: She hardly worked on the project. (if you actually mean she worked with great effort)
  Correct: She worked hard on the project.
• Using an adverb after a linking verb:
  Wrong: This cake tastes deliciously.
  Correct: This cake tastes delicious.

Practice Exercises

Explore related grammar topics:

All Grammar Topics Adjectives Adverbs Adverb Placement Comparative Structures Gradable and Non-Gradable Adjectives

Frequently Asked Questions

What is the difference between good and well?

Good is an adjective and describes a noun, as in "He's a good singer." Well is usually an adverb describing how an action is done, as in "He sings well." "Well" can also function as an adjective meaning "in good health", as in "I don't feel well."

Why is 'He sings good' incorrect?

"Good" is an adjective and cannot describe a verb like "sings". Since we need a word describing how he performs the action of singing, the adverb "well" is required: "He sings well."

Why doesn't fast become 'fastly' as an adverb?

"Fast" is one of several English words, including "hard" and "late", that keep the same form whether they are used as an adjective or an adverb. "Fastly" is not a standard English word; the correct adverb form is simply "fast", as in "He runs fast."

What is the difference between hard and hardly?

"Hard" as an adverb means "with a lot of effort", as in "She studied hard." "Hardly" is a completely different word meaning "almost not", as in "She hardly studied at all." Confusing the two completely reverses the intended meaning.

How do I know whether to use an adjective or adverb after a verb like look, feel, or smell?

These verbs can function as linking verbs, describing the subject and requiring an adjective ("She looked nervous"), or as action verbs, describing how the action was performed and requiring an adverb ("She looked nervously around the room"). Check whether the word is describing the person/thing or the manner of the action.

Why do we say 'This cake tastes delicious' and not 'deliciously'?

"Taste" here functions as a linking verb describing a quality of the cake itself, so it needs the adjective "delicious". "Deliciously" would be an adverb, which is only correct if describing how an action, like eating, was performed, not describing the cake's own quality.

Is 'I don't feel well' correct, or should it be 'I don't feel good'?

Both are used in everyday English, but they mean slightly different things. "I don't feel well" specifically refers to health, using "well" as an adjective. "I don't feel good" is also common and generally accepted, especially in casual speech, though some style guides prefer "well" for describing health.

What is a simple test for choosing between an adjective and an adverb?

Ask what the word is describing. If it describes a noun or the subject of a linking verb (how someone/something is or seems), use an adjective. If it describes how an action is performed, use an adverb, usually ending in -ly.

Is adjective vs adverb confusion a common mistake for English learners?

Yes, it is one of the most persistent grammar mistakes at every level, particularly with linking verbs, the good/well pair, and words like fast and hard that don't change form. Careful attention to what word is actually being described helps avoid this error.

Which adjective/adverb pairs should I learn first?

Start with the most frequent trouble spots: good vs well, and words that stay the same in both forms, like fast, hard, and late. Once comfortable, move on to linking verbs like look, feel, and smell, which can take either an adjective or an adverb depending on meaning.