Civil day
Defined in 2 dictionaries — Ballentine's (1916), Black's (1910)
Ballentine's Law Dictionary
James A. Ballentine · 1916
The mean solar day.
Black's Law Dictionary
Henry Campbell Black, M.A. · 1910
The solar day, measured by the diurnal revolution of the earth, and denoting the interval of time which elapses between the successive transits of the sun over the same hour circle, so that the "civil day" commences and ends at midnight Pedersen v. Eugster, 14 Fed. 422.
Defined under Day in Black's Law Dictionary.