first dorsal fin
/ˈfɜːst ɐsˈɪstənt ˈkamɹəɹ ˈɒpəɹˌeɪtə/
n
中文：第一背鳍
Meaning：Swimming appendage formed of a membrane and usually prickly rays located on the middle anterior dorsal portion of the body; it provides stability.
中文：第一背鳍