noun
pectoral fin
The pair of fins located on the sides of a fish, behind the gills, used for steering and balance.
魚の胸鰭は、方向を変えるときに使われる。
A fish's pectoral fins are used when changing direction.
この熱帯魚は胸鰭が大きくて美しい。
This tropical fish has large, beautiful pectoral fins.
Compound of 胸 (muna, 'chest') and 鰭 (hire, 'fin'), with rendaku voicing of hire to bire.