The term "time horizon" refers to the length of time that an investment is held before it is sold or matures. It represents the period over which an investor expects to achieve their investment goals, and can vary depending on factors such as the type of investment, market conditions, and individual investor preferences. A longer time horizon typically allows for greater potential returns due to the power of compounding, but also carries more risk in terms of fluctuations in the market value of the investment over time.