discrete group
discrete subgroup of a topological group G is a subgroup H such that there is an open cover of H in which every open subset contains exactly one element of H; in other words, the subspace topology of H in G is the discrete topology
en-US/dɪsˈkɹit ˈɡɹup/
en-GB/dɪˈskɹiːt ˈɡɹuːp/