A couple of years ago I coined the word peeververein (peever, "peevish complainer" + verein, Ger., "club," "association") to identify pedants forever carrying on about violations of their bogus rules of grammar.
This week, I discovered that we already had a word for them.
Simon Horobin, Professor of English Language and Literature at Oxford and author of the just-published How English Became English, tweeted as @SCPHorobin: "Dr Johnson makes a useful distinction between grammarian 'philologer' and grammaticaster 'mean verbal pedant'."
The Oxford English Dictionary defines grammaticaster as "a petty or inferior grammarian. (Used in contempt.)" It identifies the first use of the word in Ben Jonson's Poetaster (1601). The –aster suffix clamped on to grammatic, the OED explains, expresses "incomplete resemblance, hence generally pejorative," as when Jonson appends it to poet.
Poetaster has survived. Vera Pavlova sneers in "Heaven Is Not Verbose: A Notebook" in Poetry, April 2012: "A slip of the tongue can not happen to a poetaster. In poetry, to commit such a slip you need to have a tongue to speak with."
But grammaticaster, despite the platoons, battalions, and regiments of poseurs blaring rubbish about language, remains in obscurity.