What does Delta mean?

Delta is a highly versatile word and symbol with different meanings depending on context, but its core meaning is change or difference. Originating from the fourth letter of the Greek alphabet, uppercase Δ and lowercase δ, delta is used in mathematics and science to denote change, calculated as final value minus initial value. For example, ΔT means change in temperature. In geography, a delta is a landform that forms at the mouth of a river where the river deposits sediment as it splits into smaller channels before entering an ocean, lake, or sea, often forming a triangular shape like the Nile Delta or Mississippi Delta, which are known for fertile soil. In the NATO phonetic alphabet used by military and aviation, Delta represents the letter D. In Greek life, Delta refers to fraternities and sororities such as Delta Sigma Theta, Delta Gamma, and Delta Tau Delta. In finance and options trading, delta is a critical risk metric that measures how much an option's price moves relative to a $1 move in the underlying stock, ranging from 0 to 1 for calls and -1 to 0 for puts, and also approximates the probability of expiring in the money. In computing, delta means the difference between file versions. In chemistry, δ means partial charge. Overall, delta means change, difference, junction, or the letter D.