ultraproduct
Noun
Meaning
English Wikipedia has an article on:ultraproductWikipedia
ultraproduct (plural ultraproducts)
(mathematics) A quotient of the direct product of a family of structures
Examples
For example, a non-principal ultraproduct of finite fields is a pseudo finite field; i.e., a PAC field having exactly one extension of any degree.
The ultraproduct construction in model theory uses ultrafilters to produce elementary extensions of structures.