Translation

根拠の薄い / 弱い / かろうじて保たれた

Meaning

Tenuous means very weak, uncertain, or based on little evidence, especially a link, argument, claim, or position. It does not mean careful or temporary. The learner trap is confusing tenuous with tentative or tenacious.

Examples

• その二つの事件の関連はかなり薄いです。
  The connection between the two events is tenuous.
• 彼の主張は根拠が薄く、説得力がありませんでした。
  His argument was tenuous and unconvincing.