full-moon

The compound "full-moon" is a transparent descriptive term from Old English, combining two native Germanic elements. The word "full" derives from the Proto-Indo-European root pelə-, meaning "to fill," which evolved into the concept of completeness. "Moon" originates from the Proto-Indo-European mēns-, meaning "moon, month," reflecting the ancient observation of lunar cycles as a measure of time. The literal combination, "the complete moon," directly and logically names the phase when the moon's entire illuminated hemisphere is visible from Earth, representing a peak in its monthly cycle.

Structure: full (complete) + moon (the Earth's natural satellite) - full: From Old English full, meaning "complete, entire, abundant." It is of Germanic origin, related to Dutch vol and German voll, from an Indo-European root shared by Latin plenus "full." - moon: From Old English mōna, meaning "the heavenly body that orbits Earth." It is of Germanic origin, related to Dutch maan and German Mond, from an Indo-European root shared by Latin mensis and Greek mēn (both meaning "month").