The word "subplane" defines a subset of a larger plane. Some synonyms for this word include "subspace," which refers to any subset of a vector space, "subspace plane," which is a subset of a projective plane, and "submanifold," which is a subset of a higher-dimensional manifold. Other synonyms include "subfield," which refers to a subset of a larger field, and "subgraph," which is a subset of a larger graph. "Subring" refers to a subset of a larger ring, while "submodule" is a subset of a larger module. Each term has a specific context in which it is used to describe a subset of a larger structure.