also: ファイ · パイ
unclassified
diameter symbol
Technical symbol used in engineering and mathematics to denote diameter. In Japanese, it is commonly read as まる, but the readings ファイ and パイ are also used.
図面に⌀50と書いてある。
The drawing says ⌀50.
このパイプの外径は⌀30ミリです。
The outer diameter of this pipe is ⌀30 mm.