二等航海士 にとうこうかいし Meanings Noun second mate; second officer See also: 一等航海士 (いっとうこうかいし). Kanji 二 two. Read as ニ. 等 equal. Read as トウ. 航 navigate. Read as コウ. 海 sea. Read as カイ. 士 man. Read as シ. Jinuma: Japanese Dictionary · Word lists