Several working as one toward a shared end. A team differs from a group by having something it is for.
Old English tēam (a set of draught animals harnessed together, offspring, a family), from Proto-Germanic *taumaz (something drawn, a rein); several working toward a shared end were first yoked to the same load.
Several working as one toward a shared end. What separates a team from a group is having something the whole of it is yoked to.