Black Hole
A black hole is a region of space in which the gravitational field is so powerful that nothing can escape after having fallen past the event horizon. The name comes from the fact that even electromagnetic radiation (e.g. light) is unable to escape, rendering the interior invisible. However, black holes can be detected if they interact with matter outside the event horizon, for example by drawing in gas from an orbiting star.[Wikipedia.org]
Dark Mat­ter
En­ig­mat­ic sub­stance that as­tron­o­mers rec­og­nize thanks to its ef­fect on oth­er ob­jects, but which they can’t ac­tu­ally find.
Dark matter also plays a central role in structure formation and galaxy evolution, and has measurable effects on the anisotropy of the cosmic microwave background. All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which interacts with electromagnetic radiation: the remainder is called the “dark matter component” [wikipedia.org].

Dark En­er­gy
A force that be­came dom­i­nant in the Un­iverse only re­cently in as­tro­nom­i­cal time. Sci­en­tists don’t know what dark en­er­gy is, but it seems to work op­po­site gra­vity and to speed up an on­go­ing ex­pan­sion of the Un­iverse . Dark En­er­gy coun­ter­acts gra­vity.

WMAP cold spot (Gaping “hole” in the cosmos)
In August of 2007 two papers appeared within days of each other on astro-ph. Both have used an extragalactic survey (the NVSS) to demonstrate that the density of radio sources as projected on the sky is anomalously low in the direction towards the Cold Spot.
Although voids like this are known in the universe, this void is an unusually large supervoid, perhaps 1000 times larger than expected typical voids. This void is somewhere between 6-10 Billion lightyears away and nearly one Billion lightyears across.