Things that are interchangeable can be exchanged with each other without it making any difference.
例句
His greatest innovation was the use of interchangeable parts...他最大的革新在于使用了可互换的零件。Every part on the new models is interchangeable with those on the original.新款上的每一个零部件与原先的都可互换。
英汉词典释义
adv.
可交换地;可替换地
These two words can be used interchangeably.这两个字可以换用。