Slight care or diligence means such care or diligence as a person of ordinary prudence usually exercises about one's own affairs of slight importance.
Gross negligence is, to all intents and purposes, no care at all.
It is the lack of the care that the most inattentive and thoughtless persons seldom fail to take of their own affairs. It shows a reckless temperament. It is a lack of care that is practically willful in it's nature. Conduct arising from momentary thoughtlessness, inadvertence, or from an error of judgment is not gross negligence, because it neither shows a reckless temperament nor a lack of care that is practically willful.