IPA: /ˈpɜːrʧəsər/
KK: /ˈpɜrʧəsər/
A person who buys something, especially in a business context.
The purchaser signed the contract to buy the new equipment.
Purchaser → It is formed from "purchase" (from Old French *pourchacier*, meaning to pursue or seek) and "-er" (meaning a person who). A purchaser is a person who seeks to buy something.
Think of someone who is 'seeking' ('pourchacier') to buy something — that's why a purchaser is someone who buys.