Both high and highly are standard English words, but they do different jobs. High commonly describes a position, level, amount, price, pitch, or degree. It can be an adjective, an adverb, or a noun. Highly is an adverb that usually means “to a great degree” or “with strong approval.”
The choice depends on what the word modifies and what the sentence means.
Quick Answer
Use high before a noun or when describing an elevated position or level: “a high shelf,” “prices are high,” or “the ball flew high.” Use highly to strengthen an adjective, participle, or verb: “highly effective,” “highly respected,” and “I highly recommend it.”
They are related, but they are not freely interchangeable.
Why People Confuse Them
Many adverbs end in -ly, so readers may assume that highly is simply the adverb form of high. The problem is that high already works as an adverb in sentences such as “The eagle flew high” and “Aim high.”
Their meanings also overlap around the idea of an upper level. Still, high often points to position, measurement, or a result, while highly usually expresses degree, rank, or approval.
- High: Commonly describes height, level, amount, cost, pitch, or an elevated result.
- Highly: Commonly means very, greatly, at an important level, or with strong approval.
Key Differences At A Glance
| Context | Best Choice | Why |
| Before a noun | high | It works as an adjective: “high demand.” |
| After a linking verb | high | It describes the subject: “Demand is high.” |
| Physical position or direction | high | It means far above the ground: “The kite flew high.” |
| Great degree before an adjective | highly | It strengthens the adjective: “highly effective.” |
| Before a past participle | highly | It marks degree or status: “highly rated.” |
| Strong recommendation | highly | “Highly recommend” is the standard expression. |
| Favorable opinion | highly | Say “think highly of,” not “think high of.” |
| A test or rating result | high or highly | Both can work, depending on sentence structure and emphasis. |
Meaning and Usage Difference
High is most often an adjective. Before a noun, high appears in phrases such as “a high price.” It can also follow a linking verb, as in “The price is high.” Beyond physical height, the word can describe temperature, risk, quality, speed, volume, expectations, or social rank.
High also works as an adverb without an -ly ending. In that role, it usually means “at or to an elevated position, level, amount, or pitch.” For example, a bird can fly high, a singer can sing high, and a student can aim high.
Highly is only an adverb in standard modern usage. It often modifies adjectives and past participles: “highly successful,” “highly sensitive,” “highly trained,” and “highly anticipated.” It can also modify a verb, as in “I highly recommend this dentist.”
The key is meaning, not the ending alone. “The plane flew high” describes where it flew. “The pilot was highly trained” describes the great degree of the pilot’s training.
For a trusted dictionary reference, read <a href=”https://www.merriam-webster.com/dictionary/highly” target=”_blank” rel=”noopener noreferrer”>Merriam-Webster’s definition of “highly”</a>.
Tone, Context, and Formality
High is neutral and common in both conversation and formal writing. It often sounds direct because it names a level or position: high costs, high pressure, or a high score.
Highly is also standard, though some combinations sound more polished or evaluative. Phrases such as “highly qualified,” “highly regarded,” and “highly probable” are common in professional or academic contexts. In everyday speech, “I highly recommend it” remains completely natural.
Formality does not create the main difference. Grammar, meaning, and established word combinations matter more.
Which One Should You Use?
Choose high when it directly describes a noun: “high rent,” “high energy,” or “high expectations.” Also choose it after a linking verb: “Rent is high.”
Use high as an adverb when the idea involves position, direction, pitch, or an achieved level: “Jump high,” “Hold your head high,” or “The restaurant ranks high on my list.”
Choose highly when you mean “very” or “to a great degree,” especially before an adjective or participle: “highly unusual,” “highly skilled,” or “highly recommended.” Use it in established approval phrases such as “speak highly of” and “think highly of.”
With verbs such as score and rank, both forms may appear. “She scored high on the test” emphasizes the result. “The product scored highly for safety” emphasizes strong performance under a criterion.
When One Choice Sounds Wrong
Use “The bird flew high,” not “The bird flew highly.” Flying at a great height is a matter of position.
Use “She is highly qualified,” not “She is high qualified.” Here, an adverb must strengthen the adjective qualified.
Use “I think highly of my manager,” not “I think high of my manager.” The first version is the established expression for having a favorable opinion.
Also, highly cannot replace very before every adjective. “Highly tall” sounds wrong because physical height normally takes “very tall” or a direct measurement.
Common Mistakes (and Quick Fixes)
A common mistake is treating highly as the automatic adverb for every use of high. Fix the sentence by checking the meaning. When it answers “where?” or “to what level?” after a movement or position verb, high is often correct: “The balloon rose high.”
Another error is putting high before an adjective or participle. Change “high successful” to “highly successful” and “high recommended” to “highly recommended.”
Writers also mix up noun phrases and verb phrases. Say “She has a high opinion of him,” but “She thinks highly of him.” In the first sentence, high modifies the noun opinion. In the second, highly modifies thinks within an established expression.
For a person’s physical height, use tall, not high: “He is tall.”
Everyday Examples
The new apartment has high ceilings, but the monthly rent is also high.
Our team has high expectations because the new director is highly experienced.
The basketball bounced high after it hit the rim.
This restaurant is highly rated, and I highly recommend the grilled salmon.
Gas prices remain high in several cities.
The candidate is highly qualified for the position.
Maya scored high on her chemistry test.
The hotel scored highly for cleanliness and customer service.
The shelf is too high for the child to reach.
Her former coworkers speak highly of her leadership.
Dictionary-Style Word Details
Verb
High: Not commonly used as a verb in standard modern US English.
Highly: Not used as a verb. It functions as an adverb.
Noun
High: Can be a noun meaning an upper point, level, temperature, score, or feeling of excitement. Examples include “a record high” and “today’s high.”
Highly: Not used as a noun in standard English.
Synonyms
High: Closest plain alternatives depend on the meaning: elevated, upper, great, intense, expensive, or lofty. Low is the clearest general antonym in many contexts.
Highly: Closest plain alternatives include very, greatly, extremely, strongly, and favorably. Possible opposites depend on context and may include slightly, poorly, or unfavorably.
Example Sentences
High: “The temperature will remain high through Friday.” “The hawk circled high above the field.”
Highly: “The course is highly practical.” “Customers rate the service highly.”
Word History
High: This is an old English word with Germanic roots. Its meanings have long centered on height, elevation, rank, and degree.
Highly: This form developed from high plus the adverb ending -ly. It has long expressed ideas such as great degree, elevated rank, and favorable opinion.
Phrases Containing
High: aim high, fly high, high hopes, high demand, high time, and hold your head high.
Highly: highly recommended, highly likely, highly regarded, highly skilled, speak highly of, and think highly of.
FAQs
What is the main difference between high and highly?
High usually describes a position, level, amount, price, pitch, or measurement. It can work as an adjective or an adverb. Highly is an adverb that usually means “to a great degree” or “with strong approval.” For example, say “a high price” but “highly expensive.”
Is high an adjective or an adverb?
High can be both. It is an adjective in “a high wall” and “The wall is high.” It is an adverb in “The bird flew high” and “Aim high.” Its grammatical role depends on the sentence structure and the word it describes.
Is highly always an adverb?
Yes. In standard American English, highly functions as an adverb. It commonly modifies adjectives, participles, and verbs. Examples include “highly effective,” “highly trained,” and “I highly recommend this book.”
Should I say highly recommended or high recommended?
Use highly recommended. The word highly modifies the participle recommended and means “strongly” or “to a great degree.” “High recommended” is not standard. You can also say “This restaurant receives high recommendations,” because high modifies the noun recommendations.
Is it correct to say score high or score highly?
Both can be correct. “She scored high on the exam” is natural in everyday American English and focuses on the result. “She scored highly in customer satisfaction” sounds slightly more formal and emphasizes strong performance in a specific area.
Why do we say aim high instead of aim highly?
Use aim high because high describes a goal or level. The same applies to fly high, jump high, and hold your head high. Use highly for degree or approval, as in highly ambitious or think highly of someone.
Conclusion
Use high for a height, level, amount, cost, pitch, or direct description: “a high wall,” “prices are high,” and “the kite flew high.” Use highly for great degree or strong approval: “highly effective,” “highly respected,” and “I highly recommend it.”
Remember that high can already be an adverb. The correct choice comes from the sentence’s meaning and structure, not simply from adding -ly.
High usually describes a position, level, amount, price, pitch, or measurement. It can work as an adjective or an adverb. Highly is an adverb that usually means “to a great degree” or “with strong approval.” For example, say “a high price” but “highly expensive.”
High can be both. It is an adjective in “a high wall” and “The wall is high.” It is an adverb in “The bird flew high” and “Aim high.” Its grammatical role depends on the sentence structure and the word it describes.
Yes. In standard American English, highly functions as an adverb. It commonly modifies adjectives, participles, and verbs. Examples include “highly effective,” “highly trained,” and “I highly recommend this book.”
Use highly recommended. The word highly modifies the participle recommended and means “strongly” or “to a great degree.” “High recommended” is not standard. You can also say “This restaurant receives high recommendations,” because high modifies the noun recommendations.
Both can be correct. “She scored high on the exam” is natural in everyday American English and focuses on the result. “She scored highly in customer satisfaction” sounds slightly more formal and emphasizes strong performance in a specific area.
Use aim high because high describes a goal or level. The same applies to fly high, jump high, and hold your head high. Use highly for degree or approval, as in highly ambitious or think highly of someone.
