* Nani (नानी): This is used for your mother's mother.
* Dadi (दादी): This is used for your father's mother.
You can also use the more formal terms:
* Mataji (माताजी) - This is a respectful way to address your grandmother, regardless of whether she is your mother's or father's mother.
* Grandmother (ग्रैंडमदर) - This is the English word, which is also understood in Hindi.
The choice of word depends on the context and your relationship with your grandmother.