cap off

verb

1. To finish by making one last addition.
2. To glue a relatively uncomplicated compact manifold to a manifold of the same dimension along (a component of the latter's boundary).

   “a. 1997, Rob[ion] Kirby, "Problems in Low-Dimensional Topology", problem 3.21, in, 1997, William H[ilal] Kazez, editor, Geometric Topology, proceedings of the 1993 Georgia International Topology Conference, AMS/IP Studies in Advanced Mathematics 2, American Mathematical Society, →ISBN, part 2, page 163, Let X be an acyclic 2-complex and M an abstract regular neighborhood of X; ∂M_0=S², so cap off to get a homology 3-sphere M³.”

   “a. 1997, Michael T. Anderson, "Scalar Curvature and Geometrization Conjectures for 3-Manifolds", in, 1997, Karsten Grove and Peter Petersen, editors, Comparison Geometry, Mathematical Sciences Research Institute Publications 30, →ISBN, page 53, Note, however, that when one cuts a 3-manifold along an incompressible torus, there is no canonical way to cap off the boundary components thus created, as is the case for spheres. For any toral boundary component, there are many ways to glue in a solid torus... .”