The film was poorly made and can only be described as third-rate.

third-rate 是由序数词 third（第三）和形容词 rate（等级）组成的复合形容词，字面意思是"第三等级的"，引申为"低劣的、次等的"。 third-rate 常用来形容质量差、水平低的事物，在中文里对应"三流的"这个表达。