Referring to this question it seems that English does not have the equivalent of "both" for three items. Although it would seem to be a useful word, I am unaware of its existence in any languages. Is there any language that has such a word?
It appears that Hindi has a generic form that accommodates any number at all.
Number Hindi word Adj 2 do donõ 3 teen teenõ 4 chaar chaarõ
However, as the numbers get bigger, it appears§ to be more idiomatic to switch to a form that's similar to English.
tum chaarõ ladke mere saath aaoo.
All four of you boys come with me.
tum saare chalis ladke mere saath aaoo.
All forty of you boys come with me.
§ — I speak the language fluently, but I'm not a native speaker.
ทั้ง [tʰáŋ] is often used for this purpose.
กัน [gan] (one another), e.g. ต่อกัน [tò-gan] (mutually).
I guess, most (if not all) isolating languages would have such a word, and most likely it would be the same as "together", "also", or "one another".
Also, Hebrew has dual and triple inflection forms for certain nouns.
When I was studying Generalized Quantifier Theory as part of a Formal Semantics class a few years ago in college, this came up. If I recall correctly, the professor said that there weren't any languages which had a quantifier that had an identical meaning to both, but for the number 3. I don't think there was any real backing up of that assertion.
Certainly there are no major languages that I know of that have this property.