is,

Reverance and love toward God, and sgowing this love with obedience to His will, and devotion to serving Him.

Piety is also, "Reverence of parents or friends, accompanied with affection and devotion to their honor and happiness."
(Webster's 1828)

But if any widow have children or nephews, let them learn first to shew piety at home, and to requite their parents: for that is good and acceptable before God.
1 Timothy 5:4