Formal:
* કાકા (kaka): This is the most common and formal way to address an uncle.
* મામા (mama): Used for a maternal uncle (brother of one's mother).
* ફુઆ (fua): Used for a paternal uncle (brother of one's father).
* અંકલ (ankal): This is the English word used in Gujarati, often in informal settings.
Informal:
* કાકુ (kaku): A more informal way to call an uncle, often used by younger people.
* મામાજી (mamaji): A more affectionate term for maternal uncle.
* ફુઆજી (fuaaji): A more affectionate term for paternal uncle.
The best way to address an uncle depends on the specific relationship and the level of formality required.