What defines a nanowire?

A nanowire is specifically defined by its size and structure, characterized by having a diameter in the nanometer range (typically less than 100 nanometers). This nanoscale size allows for unique electrical, optical, and mechanical properties, which are significantly different from those of bulk materials. The large surface area to volume ratio and quantum effects at this scale contribute to these distinctive properties, making nanowires highly valuable in various applications such as electronics, medicine, and energy storage.

Options mentioning larger scales, such as the meter range, do not fit the definition of a nanowire since they exceed the nanometer scale. Additionally, a uniform thickness does not specifically pertain to nanowires, as other types of materials can also be described this way. The option regarding fiber used in textiles is unrelated to the concept of nanowires altogether, illustrating the specificity of the definition associated with nanostructures.