IPA: /ˈlɒdʒə/
KK: /ˈlɒdʒər/
A person who rents a room in someone else's house and lives there.
The lodger paid his rent on time every month.
Lodger → It is formed from "lodge" (from Old French *loger*, meaning to provide shelter or accommodation) and "-er" (meaning a person who). A lodger is a person who is provided with accommodation or shelter, typically in someone else's home.
Think of someone who is 'sheltered' ('loger') in a home, and the '-er' indicates that this person is the one receiving that shelter.