syntactically

From syntactic +‎ -ally.

syntactically (comparative more syntactically, superlative most syntactically)

According to the rules of syntax.
The sentence was syntactically correct, but made no sense.
- 1965 June 4, Shigeyuki Kuroda, “Generative grammatical studies in the Japanese language”, in DSpace@MIT‎, retrieved 24 February 2014:
  Thus, there is a third kind of judgment, which we shall call characterization. The wa-phrase and ga-phrase serve syntactically to distinguish predicational judgment not only from nonpredicational description but also from characterizational judgment.

according to the rules of syntax

English