The spelling of the phrase "old moons" is quite straightforward. The first word, "old," is spelled with the three letters o-l-d and is pronounced /oʊld/. The second word, "moons," is spelled with five letters m-o-o-n-s and is pronounced /muːnz/. Together, "old moons" refers to previous full moons or lunar cycles that have occurred in the past. It is a commonly used phrase in astrology and lunar folklore.
The term old moons does not have a specific etymology on its own because it is not a widely recognized term. However, if you are referring to the phrase old moon, it refers to the phase of the Moon shortly before the new moon when only a small portion of the lunar disk is visible. This term comes from the Old English word móna, meaning moon.