Rho is a letter in the Greek alphabet, represented by the symbol "Ρ" in uppercase and "ρ" in lowercase. It is the 17th letter and is often used in mathematics and science to denote various concepts, such as density in physics or correlation coefficients in statistics. In finance, Rho refers to a measure of how much the price of an option is expected to change when there is a change in interest rates. It is one of the "Greeks," which are used to assess risk and manage options portfolios, alongside other measures like Delta, Gamma, and Theta.