Shāyú (shark) is a compound noun formed by combining 鲨 (shā), which specifically refers to sharks and appears only in this word or related scientific terms, and 鱼 (yú), meaning 'fish'. Though sharks are biologically cartilaginous fish—not bony fish like most 鱼—the Chinese term groups them under the broader cultural and linguistic category of 'fish'. The word is used in everyday speech, news reports, documentaries, and marine biology contexts.

It carries no inherent positive or negative connotation but often evokes associations with danger, ocean ecosystems, or conservation efforts. Unlike English, Chinese does not distinguish grammatically between singular and plural: 鲨鱼 can mean 'a shark', 'sharks', or 'shark' as a mass noun depending on context and modifiers (e.g., 一条鲨鱼 'one shark', 许多鲨鱼 'many sharks'). It’s commonly paired with verbs like 看见 (to see), 捕捉 (to catch), or 保护 (to protect).