Word like "people" or "peanuts" (6)
I believe the answer is:
plural
(Other definitions for plural that I've seen before include "Form of noun or verb in respect of more than one" , "rivers, for example" , "Refers to two or more" , "Denotes more than one" , "Words such as "sheep" and "deer" (but not "cat" and "dog") can be this" .)