1. 剩余部分;剩余物;余下的人(或物)
    The remainder of a group are the things or people that still remain after the other things or people have gone or have been dealt with.

remainder

    e.g. He gulped down the remainder of his coffee...
           他把剩下的咖啡一口气喝了下去。
    e.g. I spent the remainder of the day feeling terrible.
           我那天余下的时间里心情都很糟糕。

2. (算术中的)余数
    In arithmetic, the remainder is the amount that remains when one amount cannot be exactly divided by another. For example, if you divide 22 by 7, the answer is 3 and the remainder is 1.

3. (因为滞销而)廉价出售（图书）
    If a book is remaindered, it is sold at a reduced price because it has not been selling very well and will not be published again.

    e.g. It failed to sell and was soon remaindered.
           此书销量不好，很快就被廉价处理了。

4. 廉价销售的书
    A remainder is a book that has been remaindered.