The same is true of sequence and series. Here the danger of confusion is more serious than with set and group. The mathematical meanings of sequence and series are so close that the distinction between them is crucial. The first day of first - semester calculus I like to talk about driving to Santa Fe. Distance from Albuquerque is a function of time.
Speed is another function of time.
But the students swallow that. They understand a graph with a time axis. Time is a function of distance. We sweat over them. But we don't acknowledge the complication caused by plain English.