Investment losses refer to a decrease in value or loss of money that occurs when an investment performs poorly, resulting in a lower return than expected. This can happen for various reasons such as market fluctuations, declining stock prices, or the failure of a business venture. Investors may experience both financial and emotional losses due to these setbacks, but they are often encouraged to view investment losses as part of the risk involved in investing and to learn from their experiences to make better decisions in the future.