protoactinium

[ proh-toh-ak-tin-ee-uh m ]
/ ˌproʊ toʊ ækˈtɪn i əm /

noun Chemistry.

British Dictionary definitions for protoactinium

protoactinium
/ (ˌprəʊtəʊækˈtɪnɪəm) /

noun

the former name of protactinium