All 5 Uses

pious
in
Babbitt
(Edited)

As he relaxed, he was pierced by the familiar and irritating rattle of some one cranking a Ford: ... Himself a pious motorist, Babbitt cranked with the unseen driver, with him waited through taut hours for the roar of the starting engine,
Chpt 1

pious = earnest in an attempt to do things correctly
[after talking about dieting] She stooped over her story while he piously sliced and gulped down the apple, discoursing: "One thing I've done: cut down my smoking."
Chpt 7 *

piously = in a highly moral manner (doing what is thought to be the right thing)
He condemned magnificently and forgave piously,
Chpt 10

piously = in a self-righteous or holier-than-thou manner
…the ideal of American manhood and culture isn't a lot of cranks sitting around chewing the rag about their Rights and their Wrongs, but a God-fearing, hustling, successful, two-fisted Regular Guy, who belongs to some church with pep and piety to it, who belongs to…
Chpt 14

piety = highly religious and moral behavior
And crooked—Say, if I told the prosecuting attorney what I know about this last Street Traction option steal, both you and me would go to jail, along with some nice, clean, pious, high-up traction guns!
Chpt 19 *

pious = self-righteous (acting as though one is highly moral when it is not true)

Definitions:

(1) (pious as in: a good, pious woman)
religious or highly moral
(2) (pious as in: a pious hypocrite)
self-righteous (acting as though one is, or believing one is highly moral when it is not true)
(3) (pious as in: cling to the pious hope)
(describing a hope or wish as) sincere, but highly unlikely
(4) (meaning too rare to warrant focus)
Much more rarely, piety can refer to devotion or faithfulness as Proust used it in the book, Swann's Way:

"...but when, as had befallen me, such an anguish possesses one's soul before Love has yet entered into one's life, then it must drift, awaiting Love's coming, vague and free, without precise attachment, at the disposal of one sentiment to-day, of another to-morrow, of filial piety or affection for a comrade."