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Wiktionary:
1. a piece of paper that entitles the holder to a discount, or that can be exchanged for goods and services
This voucher can be redeemed at any Walmart in the state until March 31 2013.
a voucher for a free kettle
This voucher entitles the bearer to a 20% discount on frozen goods.
2. a receipt

näiteid
cash voucher, sales voucher - kassatšekk
expenditure voucher- väljaminekuorder
gift voucher- kinkekaart
interest voucher - intressikupong
luncheon voucher - lõunatalong
receipt voucher - sissetulekuorder
sick voucher - haigusleht

ülevaateid
https://en.wikipedia.org/wiki/Voucher

https://khatabook.com/blog/fundamentals-of-accounting-voucher/