Japanese

Adverb

ボイン ‎(hiragana ぼいん, romaji boin)

1. with a wham, with a wallop

   拳骨 (げんこつ)でボインと殴 (なぐ)る

   genkotsu de boin to naguru

   to hit someone wham with [your] fists

2. with a boing, with a sproing

   ボインと跳 (は)ねる

   boin to haneru

   to leap with a sproing

Usage notes

Takes the particle と ‎(to).

Noun

ボイン ‎(hiragana ぼいん, romaji boin)

1. large breasts
   • 2009 April 24, Junji Majima as Daisuke Aoki, “たのしいうんどうかい (Tanoshii Undōkai) "Fun Athletic Meet"”, in Kodomono Jikan Nigakki 2nd OVA, Tokyo: Studio Barcelona, published 2009, 5 minutes, 20seconds from the start:

     "There's a teachers' relay, too, but...I wonder if you can run with breasts that big... 'Boin' sensei."

   あの子 (こ)はすごいボインだよ。

   Ano ko wa sugoi boin da yo.

   That girl is stacked. / That girl has great ****.

Synonyms

• 巨乳 (きょにゅう) ‎(kyonyū)