In defining grammar, Lindley Murray wrote "English grammar is the art of speaking and writing the English language with propriety." Following the style of the Standard Dictionary, Dr. Murray gives one of the meanings of grammar as follows: "Speech or writing judged as good or bad according as it conforms to or violates grammatical rules; also speech or writing that is correct according to those rules."
If grammar can not be good or bad, as contended by the New York Herald's editor, then it can not be true or false. Yet Dryden wrote, "And I doubt the word 'they' is false grammar (Almanzor, II. Def. Epilogue); and Macaulay writing of Frederick the Great, said: "He had German enough to scold his servants, but his grammar and pronunciation are extremely bad (Essays; Frederick the Great). Again, elsewhere, "The letter may still be read, with all the original bad grammar and bad spelling" (History of England, IV., xviii., 245). Both phrases are permissible. Compare bad.
grammatical error: A common locution, but "an error in grammar," is to be preferred as avoiding