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top; summit; apex; peak
twelve o'clock (usu. midnight)
top of one's head; top of a helmet; (top of) scalp; crown
「天辺」 has another reading with different meanings.
山の天辺まで登ると街全体が見渡せた。
Climbing to the summit of the mountain, they could see the entire town.
子どもが木の天辺に登って降りられなくなった。
The child climbed to the top of the tree and could not get down.
登山隊はついに山の天辺に到達できた。
The team finally reached the summit.