The word "uncertainty" means not being completely sure or not having a clear idea about something. It refers to a lack of knowledge or confidence in predicting what might happen. Full definition
The strict and objective criteria of realistic model performance would be a requirement for model simulations to fall within the range of uncertainties of observed climate characteristics. (link.springer.com)
The study leaves a large range of uncertainty in how much warming black carbon actually causes. (ensia.com)
With the increase in scientific data comes a decrease in uncertainty about how the universe works. (religion.blogs.cnn.com)