Explanation:

- Group of words: Merry, convivial, hearty, and good-humoured. These words suggest a cheerful, lively, and friendly nature.

- Option 1: Jowl

- Jowl refers to the flesh of the lower cheeks or jaw, especially in animals. It doesn't relate to merry or cheerful characteristics.

- Option 2: Joyous

- Joyous means feeling or expressing great happiness and joy. It aligns with being merry but misses the nuance of conviviality and good humor.

- Option 3: Jovial

- Jovial refers to a person characterized by good humor and cheerfulness, aligning perfectly with all the original descriptors like merry and convivial.

- Option 4: Jubilee

- Jubilee is a celebration, especially one marking a significant event, and while it can be merry, it doesn't relate to personality traits.