There is a raging debate going on (and probably will go on forever) about whether the fourth dimension is time, or whether it is a 4th spatial dimension. It is not the point of this site to claim that the fourth dimension is spatial instead of being time. The point of this site is to speculate about what a fourth *spatial* dimension would be like, beyond our three spatial dimensions.
To humans going about their everyday lives, time is fundamentally different than the three spatial dimensions, since only one direction is possible with time. Some have argued that this is only because of our limited perspective. Indeed, time actually behaves like a spatial dimension when you consider it in special relativity. You can get into some quite complex, interesting, and paradoxical discussions about weird things happening with time as a dimension. However, that's not what this page is about.
Some people use the term "fifth dimension" to refer to the fourth spatial dimension. The terms "fourth dimension" and "fifth dimension" are only labels though, and you could just as easily refer to time as "gerbil land" and the fourth spatial dimension as "hamster land". Throughout these pages I refer to the fourth spatial dimension as "tetraspace". That way, there can be no debate about whether the fourth dimension is time or spatial, since the term "tetraspace" has "space" within the name.