理屈詞窮

1. • lit. having presented a flawed argument, one has nothing further to add (idiom)
2. • fig. unable to provide a convincing argument to support one's position
3. • to not have a leg to stand on

Character by character

• 理(lǐ)texture
• 屈(qū)bent
• 詞(cí)word
• 窮(qióng)poor