The Adverb of Depth: Deeply
The adverb of depth is deeply.
How deeply is formed
Depth is a noun. The adverb is built from the adjective instead: depth → deep → deeply. There is no such word as depthly.
Like high, the plain form deep is also an adverb, and the two divide the work: deep for physical depth, deeply for everything figurative.
Deeply in a sentence
| They dug deep into the hillside. | Physical depth, plain form. |
| She was deeply moved by the letter. | Emotional, so the -ly form. |
| The problem is deeply rooted in the system. | Figurative depth. |
Where it is actually used
Knowing the form is one thing; knowing the company a word keeps is what makes it sound natural. These are the patterns deeply appears in most often.
| deeply moved / concerned / troubled | Emotion. The most frequent use by far. |
| deeply rooted / embedded / ingrained | Something hard to change. |
| breathe deeply | One of the few near-physical uses of the -ly form. |
Deeply or something else?
Several adverbs sit close to deeply, and the difference is usually meaning rather than formality.
| profoundly | Formal and stronger, especially about effect: profoundly deaf, profoundly changed. |
| intensely | About concentration of feeling rather than how far down it goes. |
| thoroughly | About completeness, not depth. Thoroughly researched, not deeply researched. |
The mistake to watch for
| Incorrect | Correct |
| depthly | deeply |
Adverbs are formed from adjectives, never from nouns. Depth is the noun; deep is the adjective you need.
Why breathe deeply and not breathe deep? Both occur, but deeply dominates because the phrase is not really about physical distance – it is about the manner of breathing. Where a genuine measurement is involved, the plain form returns: the mine goes deep.
Related forms
Pronunciation: DEEP-lee, two syllables.
| Noun | depth |
| Adjective | deep |
| Adverb (literal) | deep – dig deep |
| Adverb (figurative) | deeply – deeply concerned |
Practice
Fill the gap, then check yourself.
- He was ___ affected by the news.
- The roots go ___ into the rock.
- The prejudice is ___ ingrained.
Answers: 1. deeply 2. deep 3. deeply
Frequently asked
Is depth ever used as an adverb?
No. It appears in the adverbial phrase in depth – examined in depth – but that is a preposition plus noun, not an adverb.
