Grammatical

A grammatical sentence follows the rules of grammar for its particular language. Grammaticality does not necessarily entail that the sentence is not an anomaly or that it is intelligible by native speakers of that language. It only refers to the compliance with underlying syntactic rules. Grammaticality is closely related to acceptability, which is an independent attribute.

Examples
A grammatical (and acceptable) sentence of English:
 * More Russians have been to China than North Koreans have.

A grammatical (and unacceptable) sentence of English:
 * More Russians have been to China than I have.

An ungrammatical (and somewhat acceptable) sentence of English:
 * More Russians has to China been than North Koreans has.

An ungrammatical (and unacceptable) sentence of English:
 * More to Russians than China to North Koreans have been.