unsubstantial

adj.无实质的,不坚固的,薄弱的

不实在的；不坚固的；缺乏实质的。

形容词

1、The evidence against him was unsubstantial and lacked credibility.
对他的证据不实在，缺乏可信度。
2、The argument presented by the defendant's lawyer was unsubstantial and failed to convince the jury.
被告律师提出的论点不坚实，未能说服陪审团。