ruled surface
surface through every point of which runs a straight line which equally is on the surface
cylinder
ruled surface spanned by a one-parameter family of parallel lines
conoid
a ruled surface, whose rulings (lines) fulfill the additional conditions that ① all rulings are parallel to a plane (the directrix plane) and ② all rulings intersect a fixed line (the axis)
right conoid
ruled surface made of lines orthogonal to an axis
developable surface
type of surface
conical surface
union of all the straight lines that pass through a fixed point and intersect a fixed space curve