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Delta Definition, Examples & Common Usage Explained (2 meaning)
Meaning 1：river mouth alluvial fan (delta)
delta
/ˈdeltə/
n.
A triangular-shaped area of land where a river splits into several smaller rivers before flowing into a sea or lake.
river mouth alluvial fan
➕
/ˈrɪvər maʊθ əˈluːviəl fæn/
n.
A low-lying, often triangular area of sediment deposited at the mouth of a river where it enters a larger body of water.
📘 Details & Usage
📖 Root Explanation
From the Greek letter Δ, ultimately from Phoenician "daleth," meaning "door."
💡 Mnemonic
Deltas look like the triangular Greek letter D (Δ) where a river meets the sea.
📖 Example
From the airplane window, you could clearly see the green and fertile delta where the river met the ocean.
From the airplane window, you could clearly see the green and fertile river delta where the river met the ocean.
🔗 Collocations
river delta – A delta formed by a river
delta formation – The geological process of creating a delta
fertile delta – A delta with rich soil good for farming
🔄 Synonyms
estuary (n.) – The tidal mouth of a large river, where the tide meets the stream.
alluvial plain (n.) – A largely flat landform created by the deposition of sediment over a long period.
📖 Cultural Story
The word entered English via Greek, where 'delta' was the name of the fourth letter (Δ), due to its triangular shape. This shape naturally described the landform at a river's mouth. The use of Δ in science to denote 'change' comes from 18th-century calculus.
Meaning 2：Greek letter or symbol for change (delta)
delta
/ˈdeltə/
n.
The fourth letter of the Greek alphabet, written as Δ or δ. Often used in science and math to mean 'change' or 'difference'.
Greek letter or symbol for change
➕
/ɡriːk ˈletər ɔːr ˈsɪmbəl fɔːr tʃeɪndʒ/
n.
The fourth letter of the Greek alphabet (Δ, δ). In mathematics and science, the uppercase form (Δ) is commonly used to signify a change or difference in a quantity.
📘 Details & Usage
📖 Example
In the physics formula, the triangle symbol, or delta, represents a change in temperature.
In the physics formula, the triangle symbol, or delta, represents a change in temperature.
🔗 Collocations
delta symbol – The character Δ used in notation
delta variant – A named variant of a virus (e.g., SARS-CoV-2), following Greek letter naming conventions
calculate the delta – To compute the difference between two values
🔄 Synonyms
change indicator (n.) – A symbol or notation that signifies a change.
difference symbol (n.) – A character used to denote a difference between quantities.
🚫 Antonyms
constant (n.) – A value that does not change; the opposite of a variable quantity represented by delta.
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