µm
µm — noun
1. a written symbol that stands for the unit of length called a micrometre (or micr
a written symbol that stands for the unit of length called a micrometre (or micron); one µm equals one millionth of a metre, and scientists use it to describe objects that are too small to see without a microscope — such as bacteria, cells, and particles of dust or pollution.
The lab report showed the dust particle was about ten µm wide.
µm + adjective of dimension (wide)
Doctors sometimes use µm to describe the size of human cells and tiny blood vessels.
use µm to describe [measurement]
Under the microscope, each human hair measured roughly seventy µm across.
The research team found bacteria smaller than one µm living in the hot spring.
A good face mask has filter holes smaller than three µm to block dust and germs.
- micrometre
the full name that the symbol µm stands for; used in formal scientific writing
- micron
the older, shorter name for the same unit; still common in industry and some technical fields
文法句型
numeral + µm
µm + adjective of dimension
用法筆記
The symbol µ is the Greek letter mu. In science writing, µm always appears with a numeral; do not use it alone (write '50 µm', not 'several µm'). The alternative name 'micron' means the same thing and is sometimes used in informal technical contexts.