IPA: //ˈpeɪər//
KK: /ˈpeɪər/
A person or organization that makes a payment, especially in a financial context.
The payor is responsible for settling the invoice by the due date.
Payor → The word is formed from "pay" (from Old French *paier*, meaning to pay or settle a debt) and the suffix "-or" (meaning one who). A payor is one who pays or settles a debt.
Think of someone who 'settles a debt' ('pay') — the '-or' indicates a person. So, a payor is simply a person who pays.