What does micron mean?
A micron is a metric unit of length equal to 10⁻⁶ metres, or one millionth of a metre. The word is especially common in scientific and engineering contexts, where it describes microscopic particles, fibres, surface textures, or dimensions on the micrometre scale; it is also written “micrometre” in British English and “micrometer” in American English. In biology and materials science, the term helps distinguish scales that are too small for direct visual judgment but can be measured precisely with instruments. A micron may also refer to a minute particle of that size, particularly in environmental and workplace discussions of dust. The unit is commonly abbreviated µm, and the plural “microns” is standard in technical prose as well as general scientific writing. Although the name of the unit is sometimes abbreviated further to a single letter in specialist contexts, “micron” remains the clearest ordinary English term for a millionth of a metre.
nounA metric unit of length equal to one millionth of a metre (10⁻⁶ m), commonly abbreviated µm. The term can also refer to a minute particle or object measured on roughly that scale.
- A unit of length equal to one millionth of a metre (10⁻⁶ m), commonly abbreviated µm.
- A minute particle or object measured on roughly that scale.
"The polished surface contained scratches only a few microns deep."
"The bacterium is approximately two microns long."
"The machining tolerance was only one micron."
The standard plural is used for both the unit and the sense meaning a minute particle.
"The fibers are only a few microns in diameter."
A micron is a millionth of a metre—yet that tiny scale is where nanomaterials begin to matter.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does micron come from?
The word comes through French micron from Greek mikron, the neuter form of mikros, meaning “small.” It was adopted in English as the name for the metric unit one millionth of a metre and also came to denote an exceedingly small particle. Related words such as microscope, microscopy, microbe, and microphone ultimately draw on the same Greek element meaning “small,” though their formations and meanings differ.
How micron is actually used
The term is neutral and technical, occurring in scientific writing, engineering, biology, and general science reporting. British spelling normally uses micrometre for the unit, while American spelling commonly uses micrometer; the symbol µm is standard in scientific prose.
Easily confused with micron
A micrometre, written micrometer in American English, is the unit equal to one micron; a micrometer in the traditional tool sense is an instrument for measuring small distances.