chouchou チョウチョウ

Translation

chouchou means "Butterfly" in English.

Swimming Stroke

batafurai バタフライ generally refers to the Butterfly stroke used in swimming.^[1]

chouchou is normally written with katakana, as チョウチョウ.
chouchou written with hiragana is ちょうちょう.

chouchou written with kanji is 蝶々.
This word contains non-jouyou kanji 常用漢字.

chouchou may also be written as 蝶蝶.

ちょ is a compound kana representing a single syllable with multiple characters.
The kurikaeshi 々 symbol repeats the kanji that comes before it, so 蝶々 is the same thing as 蝶蝶.

Beware: some kanji that are difficult to handwrite are easy to type on the computer, which may skew the usage statistics.