What does "cylindrical" mean?

Cylindrical: Having the form of a cylinder, or of a section of its convex surface; partaking of the properties of the cylinder. Cylindrical lens, a lens having one, or more than one, cylindrical surface. -- Cylindric, or Cylindrical, surface (Geom.), a surface described by a straight line that moves according to any law, but so as to be constantly parallel to a given line. -- Cylindrical vault. (Arch.) See under Vault, n.