noun
involute
Rare mathematical term for the curve traced by a point on a taut string unwinding from another curve. The loanword インボリュート is the usual modern term.
See also: インボリュート
伸開線は、円のインボリュート曲線を指すことがある。
伸開線 can refer to the involute curve of a circle.
In this old mathematics book, the notation 伸開線 is used.