1. 镤：protium 氢元素 | protoactinium 镤 | protocol 协议
2. 镤 (名)：protium 氕 (名) | protoactinium 镤 (名) | protocol suite 协议封包, 决定网络资料传送方案的一组协议 (计算机用语)
noun
1. a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
Synonym: protactinium Pa atomic number 91