Formal:
* அத்தைமா (Aththaimaa): This is the most common and formal way to refer to a maternal grandmother. It literally translates to "mother's sister," but it's used specifically for maternal grandmother.
Informal:
* பாட்டி (Paatti): This is a general term for grandmother and can be used for both maternal and paternal grandmothers.
* அம்மாமா (Ammama): This is a less common term, but it can be used informally for maternal grandmother. It literally translates to "mother's mother," but it's not as widely used as "Aththaimaa."
Other options:
* மாமியார் (Maamiyaar): This term is typically used for the mother-in-law, but it can also be used to refer to a maternal grandmother, especially in older generations.
* பெரியம்மா (Periyamma): This term is often used to refer to an elder sister or aunt, but it can also be used for a maternal grandmother, particularly in certain regions of Tamil Nadu.
The best way to choose the appropriate term depends on your relationship with the individual and the context of the conversation.