IPA: /ˈplɛdʒər/
KK: /ˈplɛdʒər/
A person who promises to do something or gives a commitment, often in a formal way.
The pledger agreed to donate a portion of their salary to the charity.
Pledger → It is formed from "pledge" (from Old French *plege*, meaning a promise or security) and "-er" (meaning a person who). A pledger is a person who makes a promise or commitment.
Think of someone who makes a 'promise' ('pledge') — the '-er' just means a person. A pledger is someone who promises something.