solidus (n.)youdaoicibaDictYouDict[solidus 词源字典]
late 14c., plural solidi, used of both English shilling and Roman gold coin, from Late Latin solidus, an imperial Roman coin (worth about 25 denarii), from nummus solidus, literally "solid coin," properly a coin of thick or solid metal, not of thin plate (see solid (adj.)).[solidus etymology, solidus origin, 英语词源]