Adverb
once upon a time (not comparable)
A long time ago; at some time in the past (a traditional beginning of children's stories, especially fairy tales).
I don't speak Spanish, but I could read it pretty well once upon a time.
Once upon a time there was a lady. She had no children, and no happiness either. And at first she cried for a long time, but then she became wicked... Mikhail Bulgakov
Once upon a time there was a boy who loved a girl, and her laughter was a question he wanted to spend his whole life answering. Nicole Krauss
Once upon a time there were four little Rabbits, and their names were – Flopsy, Mopsy, Cotton-tail, and Peter. Beatrix Potter
And if the man who once upon a time had been a boy who promised he'd never fall in love with another girl as long as he lived kept his promise, it wasn't because he was stubborn or even loyal. He couldn't help it. Nicole Krauss
Once upon a time there was an old country, wrapped up in habit and caution. We have to transform our old France into a new country and marry it to its time. Charles de Gaulle
Once upon a time there was a widow who had two daughters. The elder was so much like her, both in looks and character, that whoever saw the daughter saw the mother. Charles Perrault