Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

If we have a sum $\sum\limits_{i=1}^na_i$, we call the terms $a_i$ summands. In fact, in the cases of addition, subtraction, multiplication, and division, we have a large vocabulary to describe the various components; see here.

Is there an analogue of the term 'summand' for unions and intersections?

That is, for $\bigcup\limits_{i=1}^n A_i$ and $\bigcap\limits_{i=1}^nA_i$, is there a term which refers to the sets $A_i$?

share|cite|improve this question
I don't recall ever hearing a particular term for these. – Asaf Karagila Sep 5 '13 at 7:16
I always wondered what these words were for products. Good link. – poirot Sep 5 '13 at 7:25
@pbs For products, I'd call them factors. – alex.jordan Jun 10 '14 at 4:52
I don't know if I'd use \displaystyle in this post; I'd have opted for \limits instead. But there's no need to edit. It's just a reminder of that option, for future posts. – Asaf Karagila Jun 10 '14 at 7:24
@AsafKaragila: Thanks, I had only used \limits for using $\lim$ inline. I know I didn't have to edit but it does look much better. – Michael Albanese Jun 10 '14 at 8:45

I've just decided to call them "uniands", but I came here hoping there was something standard.

I believe you could get away with calling them "summands" and "factors" by analogy of $\cup$ with $+$ and $\cap$ with $\times$ (the first being the sum and product of the Boolean ring of subsets of a set, and the second being the generic terms for sum and product in a ring of any sort).

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.