Fuzzy knowledge

From Glossary of Meteorology

fuzzy knowledge

Information characterized as being not quantifiable, for example, the concept of being "foggy."

It is often confused with uncertainty, which pertains more to whether a quantity is known or not. For example, one can report present conditions as more or less "foggy," depending on the current visibility. Uncertainty, on the other hand, occurs when one tries to predict the probability that the visibility will decrease within the next few hours.