Here are some options for saying "grandma" in Swahili, depending on the context:
Formal:
* Bibi: This is the most common and formal term for grandmother.
* Mama mkubwa: This literally means "big mother," and it's another way to refer to a grandmother respectfully.
Informal:
* Mama: This simply means "mother," but it can be used to address your grandmother in a casual setting.
* Mama Mzee: This literally means "old mother," and it's a way to refer to a grandmother in an informal way.
It's best to choose the term that best fits your relationship with the person you are addressing.