sirjrneuei fu'ivla

x1 (line segment) is a neuein/neusis line segment (line element) constructed from directrix x2 (curve; not necessarily linear) to catchline x3 (curve; not necessarily linear, despite the name) which is inclined toward pole x4 (point) such that it has diastema (length) x5 (li; nonnegative extended-real number).

Not necessarily unique (specify another point through which it must pass if you wish to make it so, for example). Even better (lower) bounds can be given for the diastema x5. The differences between x1 and x5 is the same as the difference between a radius (line segment) and the length of the radius (which is a nonnegative extended-real number). This is not a method of geometric construction, but a tool/means/geometric entity which is used in such constructions.