Will/wɪl/ Definition 1 of 4Pro Tip 1/3Time Specific Use 'will' when timing is certain, especially with scheduled or planned future events. The train will depart at 6 PM. Pro Tip 2/3Instant Decisions Use 'will' for decisions made at the moment of speaking rather than premeditated ones. It's hot here; I will open the window. Pro Tip 3/3Predictions Use 'will' for predictions or expectations about the future, not past events. I think it will rain tomorrow.