What is Negligentia?

Legal Definition
Lat In the civil law. Carelessness; inattention; the omission of proper care or forethought. The term is not exactly equivalent to our "negligence," inasmuch as it was not any negligentia, but only a high or gross degree ot it, that amounted to culpa, (actionable or punishable fault.)
-- Black's Law Dictionary
Legal Definition
-- Ballentine's Law Dictionary