Simple Definition:

Time is a measurement of the duration or interval between events [things that happen] or actions [things that people do]. It is a way to keep track of the order in which things happen.

Examples:

• When you use a stopwatch to measure how long it takes to run a race, you are measuring time.
• When you look at a clock or a watch to see what time it is, you are checking the current time.

Very Simple Definition:

Time is how long something takes. For example, it takes time to eat breakfast or play a game.