ad. Out of each hundred; per hundred.n. One part in a hundred: The report states that 42 percent of the alumni contributed to the endowment. Also called per centum.n. A percentage or portion: She has invested a large percent of her salary. n. Chiefly British Public securities yielding interest at a specified percentage.adj. Paying or demanding interest at a specified percentage: a 5 1/2 percent checking account.