A lens space 
is the 3-manifold obtained by gluing the boundaries
of two solid tori together such that the meridian of the
first goes to a 
-curve
on the second, where a 
-curve
wraps around the longitude 
times and around the meridian 
times.
Lens Space
Explore with Wolfram|Alpha
References
Adams, C. C. "The Three-Sphere and Lens Spaces." §9.2 in The Knot Book: An Elementary Introduction to the Mathematical Theory of Knots. New York: W. H. Freeman, pp. 246-256, 1994.Rolfsen, D. Knots and Links. Wilmington, DE: Publish or Perish Press, 1976.Referenced on Wolfram|Alpha
Lens SpaceCite this as:
Weisstein, Eric W. "Lens Space." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LensSpace.html