Based on lineage:
* Pra-prapitamaha: This is the most common and formal term, literally meaning "great-great grandfather". It's a general term for the father of your grandfather.
* Pra-prapita-pitamaha: This is a more specific term, meaning "great-great paternal grandfather". It highlights the paternal side of the lineage.
Based on relationship:
* Pra-prapita-mahatma: This term translates to "great-great revered one", emphasizing the respect and reverence due to a great grandfather.
* Pra-prapita-vriddha: This translates to "great-great elder", highlighting the age and wisdom of a great grandfather.
Other options:
* Pra-prapita: This is a shorter version of the above terms, meaning "great-great". You can use it in conjunction with other words like "pitar" (father) or "amaha" (grandfather) to specify the relationship.
Ultimately, the best way to say "great grandfather" in Sanskrit depends on the context and what you want to emphasize.