noun
in two equal parts; right in half
Emphasizes a clean, decisive split into two equal halves; often used with verbs like 割れる, 切る, or 折る.
皿が真っ二つに割れた。
The plate broke clean in half.
彼は板を真っ二つに切った。
He cut the board right in two.
Formed from the intensifying prefix 真っ (ma-) attached to 二つ (futatsu, 'two'), with the reading shift to まっぷたつ. The exact historical derivation of the geminated consonant is uncertain, but it is a common pattern in emphatic words.