# Delta

/ˈdɛɫtə/ (US) · /dˈɛltɐ/ (UK)

Source: https://englishreference.com/word/delta
Updated: 2026-08-15

## Senses

### 1. river landform

noun · CEFR B2

a triangle-shaped area of land where a river divides into several smaller parts before entering the sea.

For teachers: a landform at the mouth of a river where it empties into a larger body of water, typically characterized by a triangular shape and distributary channels.

- The Nile Delta is famous for its rich soil and long history of farming.
- The sediment deposited at the delta creates a fertile but fragile ecosystem that is increasingly threatened by rising sea levels.

### 2. mathematical change

noun · CEFR C1 · Technical

a symbol used in math and science to show a change in an amount or value.

For teachers: the symbol Δ used to represent a difference or change in a variable quantity.

- The scientist measured the delta in temperature over the course of the hour.
- In this equation, the delta represents the net change in velocity over a specific interval of time.

### 3. Greek letter

noun · CEFR B2

the fourth letter of the Greek alphabet.

For teachers: the fourth letter of the Greek alphabet (Δ, δ), often used as a symbol in various academic disciplines.

- The professor wrote the Greek letter delta on the chalkboard.
- The uppercase delta is shaped like a triangle, which is why the river landform was named after it.

### 4. computing differences

noun · CEFR C1 · Technical

the differences between two versions of a computer file.

For teachers: the set of differences between two versions of a file or data set, often used in version control systems.

- The software update only downloads the delta to save time and data.
- By analyzing the delta between the two source files, the developer could pinpoint exactly where the bug was introduced.

### 5. phonetic alphabet

noun · CEFR B2

the word used for the letter 'D' when talking over the radio.

For teachers: the code word for the letter 'D' in the NATO phonetic alphabet.

- The pilot identified the plane as Alpha-Bravo-Delta.
- Standard radio procedure requires using 'Delta' to ensure the letter 'D' is not confused with 'B' or 'E' during transmission.

### 6. to compare files

verb · CEFR C2 · Technical

to compare two versions of a file to see what has changed.

For teachers: to perform a comparison between two versions of a file or data set to identify differences.

- We need to delta these two documents to see which one is the latest version.
- The system is designed to automatically delta the incoming data against the existing database to prevent redundant entries.

## Examples

- The Nile Delta is famous for its rich green fields.
- Farmers in the river delta rely on the annual floods to bring fresh nutrients to their crops.
- The environmental impact of the dam was felt most acutely at the river delta, where the reduction in sediment flow led to significant coastal erosion and loss of habitat.

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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.