What is the antonym of "inversion" as in "the inversion of normal word order"?
Solution 1:
Sentences using the usual word order are termed unmarked.
Wikipedia has:
... unmarked sentences (i.e. sentences in which an unusual word order is not used for emphasis) ...
See sense 2d given at Dictionary.com. Note that the term is not used solely to identify the usual form of word order; it means lacking any sort of emphasis that alternatives might carry.