물증이 · 물증을
physical evidence
Example
심증은 있지만 확실한 물증이 없어서 기소하기 어려워요.
There's a strong suspicion, but without solid physical evidence it's hard to indict.
Word parts
물 thing+증 proof
Literally 'object proof'; contrasts with 심증 'inner conviction'.
Good to know
심증은 있는데 물증이 없다 'I'm sure, but I can't prove it' is also used jokingly in daily life.