IPA: //ˈkoʊˌmeɪkər//
KK: /ˈkoʊˌmeɪkər/
A person who signs a financial document, agreeing to take responsibility for a debt if the main borrower fails to pay.
The bank required a comaker to guarantee the loan in case the primary borrower could not repay it.
comaker → It is formed from "co-" (meaning together) and "maker" (from Old English "macian", meaning to make). The word "comaker" refers to a person who makes something together with others.
Think of people 'together' ('co-') who are 'making' something — that's what a comaker does.