a phase of the moon lying between last quarter and new moon, when it appears as a waning crescent
WordReference Random House Unabridged Dictionary of American English © 2025
old′ moon′.
- AstronomySee waning moon.
- 1580–90
Collins Concise English Dictionary © HarperCollins Publishers::
'old moon' also found in these entries (note: many are not synonyms or translations):