# dense

/ˈdɛns/ (US) · /dˈɛns/ (UK)

Source: https://englishreference.com/word/dense
Updated: 2026-06-20

## Senses

### 1. packed together

adjective · CEFR B2

having parts that are very close together with little space between them.

For teachers: characterized by a high degree of compactness or a high ratio of mass to volume.

- The hikers struggled to walk through the dense forest because the trees were so close together.
- The city's dense urban core presents significant challenges for planners attempting to integrate new green spaces without displacing existing residents.

### 2. difficult to understand

adjective · CEFR C1 · Academic

containing a lot of information or difficult ideas that make it hard to read or follow.

For teachers: intellectually challenging due to a high concentration of complex ideas or obscure language.

- I found the first chapter of the philosophy book very dense and had to read it twice.
- The report was so dense with technical jargon and statistical data that even the experts struggled to extract a clear policy recommendation.

### 3. mathematical sets

adjective · CEFR C2 · Technical

used in math to describe a set where you can always find a point between any two other points.

For teachers: describing a subset of a topological space whose closure is the space itself; every point in the space is a limit point of the set.

- The teacher explained that rational numbers are dense because there is always another fraction between any two.
- In any interval of the real line, the set of rational numbers is dense, ensuring that any real number can be approximated by a sequence of rationals.

### 4. slow to understand

adjective · CEFR B2 · Informal

a slightly rude way to describe someone who does not understand things quickly.

For teachers: exhibiting a lack of mental agility or failing to grasp obvious points; slow-witted.

- I felt a bit dense when I realized the answer was right in front of me the whole time.
- He was usually quite sharp, but he seemed uncharacteristically dense when we tried to explain the new office procedures to him.

## Examples

- The fog is so dense that I cannot see the road.
- We had a hard time hiking through the dense forest because the trees were packed so tightly together.
- The philosopher's latest book is so dense with technical jargon and abstract concepts that even experts in the field find it challenging to finish a single chapter in one sitting.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.