Field days.
The plural of field is fields.
The plural of field is fields.
Field is singular.Fields is the plural.
The plural of day is days. As in "the days are bright in the Summer".
The plural form of day is days.
The plural of "day" is "days."
There is no plural: neurology is a field of medicine, not a countable noun.
The plural form for the noun day is days.
The noun 'days' is the plural form of the singular noun 'day'.
There is no plural form...... it really is the plural form for day, because it means every day.
The plural form is days. The plural possessive is days'.
Yes, day is singular; the plural form is days.