What is the definition of the word unpredictable in the context of probability theory?

An unpredictable event is an event whose probability cannot be predicted with certainty.

In other words, an unpredictable event is an event whose outcome is not determined by any known information.

The definition of the word "unpredictable" in the context of probability theory is quite broad. It encompasses not only events that are impossible to predict with certainty, but also events that are highly likely to occur even if they are not impossible to predict with certainty.

For example, the outcome of a coin toss is unpredictable, even though the probability of heads or tails is always 50%. Similarly, the outcome of a random walk is unpredictable, even though the probability of the walk taking any given path is always 0.