noun
- plural form of micron, a unit of measurement equal to one millionth of a meter
Usage: technical
Examples
- The bacteria measured only a few micra in diameter.
- Dust particles smaller than 10 micra can penetrate deep into the lungs.
- The filter removes particles down to 0.3 micra in size.
- Red blood cells are typically 6-8 micra across.
- The microscope can resolve details as small as 2 micra.
- Pollen grains range from 10 to 100 micra in diameter.