Bigeye

Part of speech: noun

Definitions

1. Any of several large-eyed marine fish, such as certain tuna, sharks and deep-water species that hunt in dim light
2. A saltwater fish with unusually large eyes, found in tropical and temperate seas and adapted to low light
3. The name given to various open-ocean and deep-water fish distinguished by their oversized eyes

Etymology: "Bigeye" is a plain compound: "big" joined to "eye," with nothing hidden in the join. The name points at what sets these fish apart. Their eyes are large relative to the body, a feature that suits animals hunting in dim water, where every bit of available light matters. The word is applied loosely to several unrelated marine species, including certain tuna, sharks and deep-water fish. Because the name describes a shared trait rather than a shared ancestry, it works more like a descriptive label than a formal classification. Each fish earns the name through its eyes, not through any common family tree.