youngness

nuoruus The state or qualities of being young or youthful; youth.
1944, (w), (w), “Puppy Room,”http://www.gutenberg.net.au/ebooks01/0100121h.html

The puppy room in the basement brimmed with youngness, with suckings, cuddlings, lickings, squirmings—puppies whose eyes were sealed against seeing, puppies whose ears were sealed against hearing for the first ten days of life (..)

I was eight years older than Arthur, and our affair had started as a crazy fling with all the beauty for me of his youngness and blackness.