What is the term for showery precipitation in the form of irregular pellets or balls of ice more than 1/5 inch in diameter?

The term for showery precipitation that occurs in the form of irregular pellets or balls of ice measuring more than 1/5 inch in diameter is indeed hail. Hail forms during thunderstorms, particularly when strong updrafts carry water droplets upward into extremely cold areas of the atmosphere, causing them to freeze. As these frozen particles fall, they can collect additional water, becoming larger as they are lifted and dropped multiple times before finally falling to the ground.

Sleet refers to small ice pellets that are typically less than 1/5 inch in diameter and form in freezing rain conditions. Frost is a thin layer of ice that forms on surfaces when the temperature drops below freezing, while ice generally refers to frozen water in any form. Thus, the distinguishing characteristics of hail, specifically its size and formation process during thunderstorms, clearly identify it as the correct answer.