The service at that restaurant was absolutely third-rate; I wouldn't recommend it to anyone.

third 是序数词"第三"，在评价体系中常表示"次等的"。 rate 是名词，意思是"等级、级别"。 third-rate 是固定搭配，字面意思是"第三等级的"，引申为"低劣的、质量差的"，用来形容非常糟糕的事物或服务。