证实 means 'to confirm' or 'to verify' — it refers to the act of establishing the truth or accuracy of something through evidence, investigation, or authoritative sources. The first character 证 (zhèng) means 'evidence', 'proof', or 'to attest'; the second character 实 (shí) means 'real', 'true', or 'substance'. Together, they form a verb emphasizing the process of turning suspicion, hypothesis, or claim into verified fact. It is commonly used in formal, academic, journalistic, and scientific contexts — for example, when researchers validate data, journalists check facts, or officials authenticate documents.

The word carries a tone of objectivity and reliability; it implies rigor rather than casual agreement. It is not used for personal feelings ('I confirm I like it') but for factual validation ('The lab results confirmed the diagnosis'). It often appears with objects like 'rumors', 'reports', 'hypotheses', 'alibis', or 'identity', and frequently follows subjects such as scientists, police, experts, or official bodies.