A splitting field is an extension field of a field
for a polynomial
such that
factors completely into linear factors in
and
does not factor completely into linear factors over any
proper subfield of
containing
(Dummit and Foote 2004, p. 536).
For example, the extension field is the splitting field for
since it is the smallest field containing its roots,
and
. Note that it is also the splitting field for
.