The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Syntax: The arrangement — the ordering, grouping, and placement — of words within a phrase, clause, or sentence; the study of the rules governing such arrangement. Some critics extend the term to encompass matters such as the complexity or completeness of these arrangements. Syntax is a component of grammar, though it is often used — incorrectly — as a synonym for grammar.
Syntax has also been viewed as one of the two components of diction (the other being vocabulary), the general character of language used by a speaker or author. The sentences “I rode across the meadow” and “Across the meadow rode I” exhibit different syntax but identical vocabulary. To replace “meadow” with “sea of grass” is to alter the vocabulary but not the syntax. And to say “Rode I across the sea of grass” is to use diction very different from “I rode across the meadow.” The combination of unusual syntax and vocabulary is a feature that often differentiates poetic diction from that of prose.