noun "the system of those sequential relations that any event has to any other, as past, present, or future; indefinite and continuous duration regarded as that in which events succeed one another." This is just the definition taken from dictionary.com, it could also be defined as a social construct, but I guess it already is by the use of the word "system", by people who care not about being to early or to late to something.

Time is an idea and a meshurment

its when you do a thing and then a thing happens i think

I think it is a way to measure how long something takes or how much change has occurred while you're doing something. For example,in the past from sunrise to sunset would be called a "day" so if I say "It took me the whole day to finish the job" how long did it take me? From sunrise to sunset and that's also how much change has occurred,at least the basic idea I think.