the GNU version of the Collaborative International Dictionary of English
n. A petty grammarian; a grammatical pedant or pretender.
The Century Dictionary and Cyclopedia
n. A petty or pitiful grammarian; one who insists upon the minutest grammatical niceties.
Word Usage
"“But great writers are fallible!”, cries the grammaticaster*, ignoring the implication in this that the grammaticaster is substantially more aware of the rules of our language than its best writers."