When a reference is used to four-dimensional co-ordinates, it is likely that what is referred to is the three spatial dimensions plus a time-line.
Taken from Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Fourth_dimension
Lengh X Width X Height X Time + Love :)
ANSWER
Not counting virtual reality, everything you know of is four-dimensional.
The fourth dimension is probably the hardest dimension to understand. It's made up of 4 parts, length x width x depth x time( L x W x De x t). Therefore, there really is no visual object that is not four-dimensional.
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