満まん塁るいホームラン

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ホ

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Meanings

1

noun

grand slam home run

baseball

Baseball term for a home run hit with the bases loaded, scoring four runs.

full, fullness, enough

塁bases, fort, rampart

ホームラン
A regular home run; 満塁ホームラン specifically means a home run with the bases loaded.
満まん塁るい
The state of having the bases loaded; 満塁ホームラン is a home run hit in that situation.

Compound of 満塁 (manrui, 'bases loaded') and ホームラン (hōmuran, 'home run'), a straightforward baseball term.