daytime, noon
昼 centers on the bright middle part of the day: daytime and noon, when the sun is highest.
昼 is the modern simplified form of 晝. The older form combined 日 (sun) with a component suggesting a boundary or limit, together expressing the idea of daytime. The modern form replaces the upper part with 尺, which is a simplification and not the original historical component.
The outer 尺 looks like a ruler measuring the day, and inside 旦 shows the sun above the horizon. Together they mark the measured daylight hours: daytime and noon.
For チュウ, picture the sun at noon directly above you, and you say 'chew' as you eat lunch: chew -> チュウ, right in the middle of the day.
noon; midday
daytime; during the day; time from sunrise until sunset; diurnal period
lunch
(afternoon) nap; sleeping during the day; siesta
lunch; midday meal
lunch; midday meal
lunch break; noon recess; noon rest period
day and night
just past noon; afternoon
morning; forenoon
early afternoon
midday; broad daylight
daytime; midday
broad daylight
daydream; waking dream
Belle de Jour (novel, film)
Japanese bindweed (Calystegia japonica)
whole day and night; 24 hours
day and night
just before noon