'凭证' (píng zhèng) is a compound noun meaning 'voucher' or 'certificate'—a physical or digital document that serves as official proof of a transaction, identity, qualification, or entitlement. The first character, 凭 (píng), means 'to rely on' or 'based on', suggesting something used as grounds for action or verification; the second, 证 (zhèng), means 'evidence' or 'certificate'. Together, they convey the idea of an authoritative item you 'rely on as evidence'.

This word appears frequently in administrative, financial, and service contexts: for example, receipts for purchases, student ID cards, vaccination records, or boarding passes. It carries a formal, neutral register and is rarely used in casual speech unless referring to official documentation. Unlike more general terms like 'document', 凭证 specifically implies functional validity—it must be accepted by an institution or system to serve its purpose.