"I feel a bit apologetic for retaining the term 'four-dimensionalism' as a name for the thesis that things have temporal parts. This is one standard usage of the term, but the term is also sometimes used (particularly in Australia) for the B-theory of time, or for the conjunction of the B-theory and the doctrine of temporal parts. The term also has the disadvantage of not wearing its meaning on its sleeve. For example, what I call four-dimensionalism implies the existence of instantaneous objects: temporal slices of spacetime worms. Since temporal slices have non-zero extension in only the three spatial dimensions, someone not familiar with the debate might expect me to be a three-dimensionalist. Despite these shortcomings, my terminology is familiar and entrenched enough to be useful, if handled with care."
--Theodore Sider, Four-Dimensionalism: An Ontology of Persistence and Time, Oxford (2001), pp. xiii-xvi.