/tə ɪmˈpjuːn krɛdəˈbɪləti (ʌv ə ˈwɪtnəs)/ – Phrase
Definition: bày tỏ sự không tin cậy (đối với nhân chứng).
A more thorough explanation: To impugn credibility of a witness means to challenge or question the reliability, truthfulness, or trustworthiness of the testimony provided by the witness in a legal proceeding.
Example: The defense attorney attempted to impugn the credibility of the witness by highlighting inconsistencies in their testimony.