There are a variety of adjectives, some spurious, that may modify “manifold” that are similar enough to confuse. Together with Google count there are: symplectic 900k, symplical 5, symplicial 366, simplectic 18k, simplical 14k, simplicial 730k. A small sample suggests that the adjectives beginning “sym” are about spaces with built-in antisymmetric tensors, while those beginning “sim” are about decomposing manifolds into simplexes.