Merriam-Webster's Word of the Day for September 05, 2008 is:

wormhole • \WERM-hohl\  • noun
1 : a hole or passage burrowed by a worm *2 : a hypothetical structure of space-time envisioned as a long thin tunnel connecting points that are separated in space and time

Example sentence:
Some science fiction writers speculate that wormholes will become the intergalactic highways of the future.

Did you know?
If you associate "wormhole" with quantum physics and sci-fi, you'll probably be surprised to learn that the word has been around since Shakespeare's day – although, admittedly, he used it more literally than most modern writers. To Shakespeare, a "wormhole" was simply a hole made by a worm, but even the Bard subtly linked "wormholes" to the passage of time; for example, in The Rape of Lucrece, he notes time's destructive power "to fill with worm-holes stately monuments." To modern astrophysicists, a wormhole isn't a tunnel wrought by a slimy invertebrate, but a theoretical tunnel between two black holes or other points in space-time, providing a shortcut between its end points.

*Indicates the sense illustrated in the example sentence.