tetracycline
/ˌtetrəˈsaɪklaɪn/noun
1- Medicine any of a large group of antibiotics with a molecular structure containing four rings【医】四环素（类）。
1.1
- These antibiotics are often obtained from bacteria of the genus Streptomyces四环素类抗生素常从链霉菌属的菌类中获取。
词源
1950s: from TETRA- + CYCLIC -INE4.