Delta (noun)

1. A triangular deposit of sand, silt, or clay at the mouth of a river formed by sediment carried by the river.
2. A flat, low-lying plain of mud or sand between branches of the mouth of a river.
3. The fourth letter of the Greek alphabet.

Origin:

From the greek letter 'δ', used to represent a change or difference.

Examples:

1. The Nile delta is one of the most fertile areas in the world.
2. The river delta was rapidly changing due to the influence of human activities.
3. The delta of a stock option is a measure of how much the option price will change with a small change in the price of the underlying stock.
4. The delta symbol is used in mathematics to represent a change or difference.
5. Aircraft flying into the Delta region are subject to certain restrictions due to the proximity of the river delta.