the whole sky; the heavens
Refers to the entire visible sky, often used in poetic or descriptive contexts. Not an everyday conversational word; more common in writing, news, or set phrases like 満天の星 (a sky full of stars).
I looked up at the star-filled sky.
The whole sky was covered with clouds, and the sun was not visible.
all over the world; throughout the world
Compound of 満 (man, 'full') and 天 (ten, 'sky, heavens'). The exact historical derivation is uncertain, but the combination naturally conveys the idea of the entire sky.