An abstract concept used to describe the linear passaage of events obsesrvable in three dimensions. The "classical" three dimensions (length, width, height) are spatial, whereas time is temporal. Time cannot be directly observed, only quantified in terms of seconds, minutes, hours, etc. Time itself is impossible to accurately illustrate in our 3-D world, but is most often represented as a line, moving in one direction at a constant rate.
Time travels constantly in one direction, and is widely believed to be irreversible.