a hard, transparent, yellowish-brown substance that was formed in ancient times from resin (= a substance produced by trees) and is used in jewellery

He has a collection of prehistoric insects preserved in amber. 他收集了很多保存在琥珀中的史前昆虫化石。

Greek philosophers discovered that when amber is rubbed against cloth, lightweight objects will stick to it.

the yellowish-orange traffic light that shows between the green and the red to warn drivers that the lights are about to change

The lights turned to amber. 交通信号变成了黄灯。