The regulation of the water level in Gatun Lake is no small task, for the Chagres is one of the world's moodiest streams.
Her fascination soothed the savage Peter in his moodiest hours.
moody mood·y (mōō'dē)
adj. mood·i·er, mood·i·est
Given to frequent changes of mood; temperamental.
Subject to periods of depression; sulky.
Expressive of a mood, especially a sullen or gloomy mood.