The lunar phase in which the Moon lies opposite the Sun as seen from Earth, so that its entire visible face is lit; it recurs about every 29.5 days.
Chuseok'sfull moon isn't always perfectly full. The lunar calendar sets day 1 at the new moon, but the Moon's elliptical orbit makes it move at uneven speed, so the true full moon often misses day 15 — in 2026 it lands two days after Chuseok, on September 27.