young moon

noun2

1. •
   The phase of the moon when it is waxing, especially before quarter moon.
2. •
   The moon when it is waxing.

   • Fred Schaaf (1983), Wonders of the Sky: Observing Rainbows, Comets, Eclipses, the Stars and Other Phenomena, page 70: “Thus you can know that it would be impossible to see a young moon at sunset if new moon had occurred just a few hours earlier.”
   • John E. Westfall (2000), Atlas of the Lunar Terminator, page 61: “The young Moon is best observed shortly after a springtime sunset, as is the case here.”