syntactically

Syntactically is an adverb related to syntax, the set of rules that govern the structure of sentences in a language or formal grammar. The term derives from the noun syntax, which itself comes from Greek roots meaning arrangement or putting together.

In linguistics, syntactically describes the structural aspects of a sentence. A sentence can be syntactically well-formed or ill-formed according to the grammar of a given language. Syntactic analysis focuses on hierarchical structure, constituent order, and dependencies, and is distinct from semantics, which concerns meaning.

In computer science and formal languages, syntactic analysis concerns the grammar of a programming language. A program that is syntactically correct conforms to the language’s syntax rules; a syntax error prevents the program from being parsed. Syntactic validity is often discussed separately from semantic validity, which concerns the program’s behavior and meaning.

Examples help illustrate usage. In English, the canonical word order is subject–verb–object, so “The cat sat on the mat” is syntactically standard. The phrase “On the mat the cat sat” is also syntactically well-formed but stylistically unusual. A sentence like “The cat the mat sat” is syntactically ill-formed, illustrating how structure affects acceptability.

Notes: The use of syntactically is formal; in everyday prose, grammatically is more common, though syntactically emphasizes structural form. Related terms include syntax, syntactic, parser, and parse tree. See also grammar and parsing.