Lat. pietas, properly honour and respect toward parents (1 Timothy 5:4). In Acts 17:23 the Greek verb is rendered "ye worship," as applicable to God.

Noah Webster's New International Dictionary of the English Language

1. (n.) Veneration or reverence of the Supreme Being, and love of his character; loving obedience to the will of God, and earnest devotion to his service.

2. (n.) Duty; dutifulness; filial reverence and devotion; affectionate reverence and service shown toward parents, relatives, benefactors, country, etc.