diameter
diameter — noun
1. the distance across a round shape, measured by a line passing through its centre
the distance across a round shape, measured by a line passing through its centre and meeting the edge at two opposite points; also used for the numerical length of that line.
Hari measured the diameter of the tree trunk before cutting it down.
measure the diameter of [round object]
A pipe with a wider diameter allows more water to flow through it.
wider diameter
Daichi drew a circle and marked its diameter with a red pencil.
The diameter of Earth is about twelve thousand seven hundred kilometres.
Walid used a ruler to check the diameter of the old coin.
文法句型
the diameter of [something]
[number] in diameter
常見錯誤
2. a unit that tells you how many times larger an object appears when seen through
a unit that tells you how many times larger an object appears when seen through a lens, microscope, or telescope, compared to how it looks with the naked eye.
Folake observed the cells under a microscope at four hundred diameters magnification.
[number] diameters magnification
The telescope's two hundred diameter setting made the craters on the moon easy to see.
[number] diameter setting
For viewing blood samples, the lab uses a lens of one thousand diameters.
Tamar adjusted the microscope to fifty diameters to examine the butterfly wing.
- magnification
more common and general term; 'diameters' is restricted to lens specifications
- power
informal shorthand ('the scope's power is 20×'); less precise than 'diameters'
文法句型
[number] diameters
at [number] diameters magnification
用法筆記
This sense is almost always used with a number (e.g., '40 diameters', '100× diameter'). In modern technical writing, '×' or 'times' is often preferred over 'diameters'.