Definitions
from Wiktionary, Creative Commons Attribution/ShareAlike License
 n. The fourdimensional continuum of the three spatial dimensions plus time.
 n. An ndimensional continuum consisting of dimensions of both space & time. Normally spacetime is considered as having 4 dimensions (x, y, z, t), but higherdimensional spacetimes are often encountered in theoretical physics, e.g. the 5dimensional spacetime of KaluzaKlein theory or the 11 dimensions of spacetime in Mtheory.
 n. A specific region of the universe with mathematically different properties than the surrounding spacetime. Synonymous with "metric" within the context of general relativity.
Etymologies
from Wiktionary, Creative Commons Attribution/ShareAlike License
Examples

My objection to punching a hole in spacetime is the same as my earlier objections.

Compared to that, the tiny risk to humanity, the planet and solar system, the galaxy and all other things that currently exist in spacetime is more than worth it.

Given that all biological processes apparently reduce to subatomic particles of matter interacting with each other and with waves of radiation in spacetime, is it fair to say that biology is essentially physics?

This may be your best post yet; asking pointed questions to try and understand another's pointofview. stunney: Given that all biological processes apparently reduce to subatomic particles of matter interacting with each other and with waves of radiation in spacetime, is it fair to say that biology is essentially physics?

And the notion that our spacetime is a "virtual reality" is not in any way incompatible with Abrahamic religions.

Only living beings in spacetime can be aware of left and right, up and down, the things that quarks do.

Even a wormhole is not a “rip” in spacetime, it is just a topological feature in spacetime.

To be able to perceive all of spacetime, is to know all future and past events in the entire universe – to be omniscient.

We can not rip or “split open” spacetime – spacetime is just spacetime – nothing exists outside of it or acts on it as a whole (ignoring possible inflationary themed pocket universes (other spacetimes) colliding with our own).

Time travel, whether you believe the mathematics that supports it are physical or not, is something that exists within spacetime (as does everything else).
whichbe commented on the word spacetime
In physics, any mathematical model that combines space and time into a single construct called the spacetime continuum. Spacetime is usually interpreted with space being threedimensional and time playing the role of the fourth dimension. (Wikipedia)
May 29, 2008