MACHO Syllabification: (MACHO)Pronunciation: /ˈmäCHō, ˈmaCHō/Definition of MACHO noun Astronomy a compact object, such as a brown dwarf, a low-mass star, or a black hole, of a kind that is thought by some to constitute part of the dark matter in galactic halos. Origin: 1990s: acronym from Massive (Astrophysical) Compact Halo ObjectMACHO in other Oxford dictionaries Definition of MACHO in the British & World English dictionary
