In this case, each cell is also a standalone battery (an 1850 I presume). Assemblage of these is either called a module or a pack.

An 18650 is a single cell. (Or a battery in modern parlance.) Now, get off my lawn! :-D Just kidding! The terminology shifted. But a cell used to be the single unit of chemistry and catode and anode that gives the native voltage. So an 18650 would be a cell. A 1.5V alkaline would be a cell. A 9V alkaline would be a battery of six cells! And so on.

I'm not saying it's wrong nowadays to say an 18650 is a battery.