The "principal value" refers to the most important or significant value in a particular context. It is the main or primary value that is considered relevant or essential. Full definition
The investment return and principal value of mutual funds will fluctuate, and shares, when sold, may be worth more or less than their original cost. (wellsfargo.com)
The question of maturity should be based on the investors perceived need for yield and risk / opportunity of a change in principal value. (arborinvestmentplanner.com)
The prices of bonds can fluctuate, and an investor may lose principal value if the investment is sold prior to maturity. (edwardjones.com)