Formal:
* Lolo: This is the most common and formal way to say "grandpa." It is used for any grandfather, regardless of the speaker's relationship with him.
* Tatay: This literally means "father," but it can also be used as a respectful term for an older man, including a grandfather.
Informal:
* Lole: This is a shortened version of "Lolo," used by younger people or close family members.
* Pa: This literally means "father" and is often used for grandfathers by their grandchildren.
Other:
* Ama: This literally means "father" and is used when referring to a grandfather in a more formal setting.
The specific term used will depend on the individual's relationship with the grandfather and the level of formality desired.