There have been many definitions of time in the past. I propose the following:

Time is a method of understanding the percieved sequence of events around us. As no time but the present can be directly experienced, the past and future do not exist. Yet, the past and present are important as they directly impact what we experience to be the present.

Impact on Social Policy. This definition would suggest that past bad deeds ought not to be considered now, and that reinforcers be it negative or positive, ought to be as close to an action as possible, if not instantaneously. Likewise, we should not get particularly upset about poor decisions and losses of the past: we have to live for today.

Failure to Predict Tomorrow. This definition diminishes plans for the future, and obscures the fact that current actions will ultimately effect tomorrow's results. A law created in the present will be on the books tomorrow, and suburban sprawl of the 1950s continues to effect us.

Tomorrow Never Comes. The present constantly evolves and becomes later in time, but you can not escape where you are in the current moment. You may despise what you have to do right now, and be dreaming of later, but you can not get to later at the current moment. You must wait for time to come around.

Time as a Constant Force. The future constantly becomes the present, and if you wait long enough, change will happen and things will get better. You can not see the future, but only know that it will inevitably become the present and then the past.