/ˈfɔr dɪˈmɛn ʃə nl, ˈfoʊr-/
of a space having points, or a set having elements, which require four coordinates for their unique determination.
having or specified by four dimensions, esp the three spatial dimensions and the dimension of time:
a four-dimensional continuum
Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Instead of string theory, four-dimensional tetrahedrons.
So far, they have succeeded in creating a stable four-dimensional spacetime, when viewed at large distances.
Stratigraphy, in essence, is the science aimed at unraveling this four-dimensional puzzle.
Same thing with the universe: it's a closed four-dimensional shape with a finite volume in three dimensions but no boundary.