noun
seaplane carrier; seaplane tender
A military vessel that carries and supports seaplanes; a specialized historical naval term.
水上機母艦は、第二次世界大戦で重要な役割を果たした。
Seaplane carriers played an important role in World War II.
航空母艦 is a standard aircraft carrier for wheeled aircraft, while 水上機母艦 specifically carries and tends seaplanes.
Compound of 水上機 (seaplane) and 母艦 (mother ship, tender).