n a trivalent metallic element of the rare earth group; occurs with yttrium
n a room in a hospital or clinic staffed and equipped to provide emergency care to persons requiring immediate medical treatment
abbr. 设备要求规格（Equipment Requirement Specification）；经济研究处（Economic Research Service）；欧洲遥感卫星（Europe Remote Sensing Satellite）；地球资源卫星（Earth Resources Satellite）