More massive objects fall faster than less massive objects.

Objects attract towards the most massive and nearest source of gravitation because of gravity. Objects are pressed away from such an object by dark energy. Such a combination causes relatively large objects to orbit other objects.

Particles that are heavy. Mass is like MASSive (massive) and massive objects could be heavy.

Massive astrophysical compact halo object, or MACHO, is a general name for any kind of astronomical body that might explain the apparent presence of dark matter in galaxy halos. A MACHO is a body composed of normal baryonic matter, which emits little or no radiation and drifts through interstellar space unassociated with any solar system. Since MACHOs would not emit any light of their own, they would be very hard to detect. MACHOs may sometimes be black holes or neutron stars as well as brown dwarfs or unassociated planets. White dwarfs and very faint red dwarfs have also been proposed as candidate MACHOs.

Very loosely, relativity says massive objects change the geometry of space/time. Bending both time and space.