essential manifold
compact manifold M whose fundamental class [M] defines a nonzero element under the natural homomorphism Hₙ(M) → Hₙ(K(π₁(M),1))
en-GB/ɪˈsɛnʃl ˈmænɪfəʊld/
compact manifold M whose fundamental class [M] defines a nonzero element under the natural homomorphism Hₙ(M) → Hₙ(K(π₁(M),1))