The word ????????, ??????? signifies 'to exercise piety, reverence': a reverential sense of having to say to God, which should be shown by the creature to the Creator, and which should especially characterise the saints towards God their Father and to the Lord Jesus. The word is translated 'piety' in the A.V. only in 1Ti 5:4. It is rendered 'holiness' in Ac 3:12, and 'worship' in Ac 17:23. In all other places it is 'godliness.' 'Piety' is a better translation, and distinguishes it from ?????????, which signifies 'worship, or fear of God,' and is translated 'godliness' in 1Ti 2:10.
This word occurs but once in the Authorized Version: "Let them learn first to show piety at home," better "toward their own household" or family.
The choice of this word here instead of the more usual equivalents -of "godliness," "reverence," and the like, was probably determined by the special sense of pietas, as "erga parentes," i.e. toward parents.