Wikipedia's (informal) definition if a time series is
"A time series is a series of data points indexed (or listed or graphed) in time order. Most commonly, a time series is a sequence taken at successive equally spaced points in time."
As sequence is defined as an indexed set of objects (often numbers), where the order of the objects is non-trivial, it would make more sense to me if it were called time sequence. As a series is (informally) defined as a sum of an infinite sequence.
So does anyone know the origin of the name "time series"? Is it just random, or is there a reason to the madness?