What does nanometre mean?
A nanometre is a metric unit of length equal to one-billionth of a metre, or 10⁻⁹ metre. The term is used to describe dimensions in nanotechnology, medicine, chemistry, physics, and engineering, where objects and features may be too small to measure conveniently in conventional units. A nanometre is also commonly used to describe the size of particles, the wavelength of some light, and the resolution of imaging equipment. It is related to the micrometre, which is one thousand times larger, but the nanometre is used for still smaller scales. The word combines the prefix nano-, meaning one-billionth in the metric system, with metre, the unit of length. Its US spelling is nanometer, and the abbreviation nm is widely used in scientific writing and specifications.
nounA metric unit of length equal to one billionth (10⁻⁹) of a metre. It is used especially in science and technology to describe very small dimensions.
- A metric unit of length equal to 10⁻⁹ metre.
"The nanoparticles were only a few nanometres across."
"The imaging technique can resolve structures smaller than 100 nanometres."
"This wavelength lies in the near-infrared region, measured in hundreds of nanometres."
The plural is formed by adding -s in both British and American English.
"Several features measured only a few nanometres in size."
A nanometre is one-billionth of a metre, so a typical DNA double helix is only about two nanometres wide.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does nanometre come from?
Nanometre combines the international SI prefix nano-, denoting one-billionth, with metre, the metric unit of length. The prefix derives from the Greek nanos, meaning dwarf or tiny, while metre derives through French from the Greek metron, meaning measure. The resulting term follows the established pattern of metric units and has a US variant spelling, nanometer. Related scientific words such as nanosecond, nanoparticle, and nanotechnology developed from the same nano- combining form.
Related word forms
How nanometre is actually used
The spelling nanometre is standard in British English, while nanometer is standard in American English. The unit is usually used in technical and scientific contexts, and its symbol is nm.
Easily confused with nanometre
Nanometer is the US spelling of nanometre; both words name the same metric unit of length.