Priscian, Latin grammarian of the 6th century, born in Cæsarea; was author of "Grammatical Commentaries" in 18 books, a standard work during the Middle Ages, and in universal use at that time.

PRISCIAN. To break Priscian's head; to write or speak
false grammar. Priscian was a famous grammarian, who
flourished at Constantinople in the year 525; and who
was so devoted to his favourite study, that to speak false
Latin in his company, was as disagreeable to him as to
break his head.