Unpredictable (adjective) - when you cannot predict or know what will happen next. EXAMPLES: The weather is so unpredictable. It was so hot early this morning and then it rains all of a sudden in the afternoon. The outcome of the competition is unpredictable. All of the contestants are good.

It means you cannot guess what will happen. Example: Bob is so unpredictable. Yesterday he helped me clean up the basement, but today he won't do anything around the house! You never know what he will do! The weather in Saint Louis is unpredictable. One day it is snowing, and the next day it is extremely hot.