Prediction of the future events. It is a special case of [prediction], in the context of [time-series].
Usually, forecasting is applied to time series data where future values of a series are predicted based on past observations. It is contrasted with prediction in Cressie & Wikle Statistics for Spatio-Temporal Data, p. 17:
Uncertainty in data, processes or parameters means that there will be uncertainty in conclusions. Statisticians call this drawing of conclusions in the presence of uncertainty, statistical inference (or just inference); in this book, inferences will be either estimation of fixed but unknown parameters, or prediction of unknown random quantities. (Notice that "forecasting," namely concluding something about the future, is a special case of "prediction.")