ungrammatical

1. (linguistics) In violation of one or more of the rules and conventions of a language as defined by the grammar, resulting in unacceptable or incorrect usage.Examples: "My Greek is not the tongue of Homer or Aeschylus but a sloppy ungrammatical sabir lacking Attic salt and tending to a saccharinity which sets my teeth on edge."; "That comment seemed to anger Ingraham, who called James’ view a “barely intelligible, not to mention ungrammatical take on President Trump.”"; "While adopting the pronoun as a nonbinary description is vastly preferable for some, Merriam-Webster says, there has also been some debate that it is ungrammatical."Synonyms: agrammatical, ungrammaticAntonyms: grammatical