an electronic device that can read the information on a credit card, etc.

To pay, just hold your card up to the card reader. 付款的时候，只需要拿着卡贴近读卡器就可以了。

a device in a computer, etc. that can move data from another device on which it has been stored

The computer was supplied with an integrated 4 in 1 card reader. 这台电脑配备了四合一读卡器。