Iteration (very basic question on terminology)

Question

A finitary union of sets $\bigcup_{n=1}^{n} S_i \leftrightarrow S_1 \cup S_2 \cup \ldots S_n$ or a series such as $\sum_{n=1}^{n} 2^{-n} = 1$, they all represent the same generic operation of iterating terms connected by the same logical ($\cup)$ or mathematical ($+$) operator. I'd like to use the proper terminology that expresses this idea of repetition of terms a set amount of times. Is that some case of iteration or recursion or is the term iteration reserved to functions? And how do we technically refer to the upper and lower limits of such repetitions?

Answer 1

As mentioned on the English Wikipedia page for "iterated binary operation", "iteration" is indeed a generic term that can be used for this sort of thing.

More specific terms like $n$-fold union/sum are mentioned on that page as well.