(Denis), or Dionysius Petavius, a French Jesuit of great erudition, born at Orleans in 1583. He entered into the society of Jesuits in 1605; and did no little honour to it by his learning, which he employed in defending the Catholic church, by criticising and abusing its adversaries. Joseph Scaliger was the person against whom he was the most inveterate; nor did he spare his friend Caiusbon when he came in his way. Petavius excelled particularly in the dark science of chronology, the learned world in general being obliged to him for some exact and nice disquisitions on this subject. His chief work, which is in great repute to this day, he intitled, Rationarum temporum. It is an abridgment of universal history, from the earliest times to 1632, in chronological order, with references to proper authorities. It was improved, and several additions made to it, by Perizonius, and others after his death. He died in 1652.

PETECHIAE, in medicine, a name given to those spots, whether red or of any other colour, which appear in malignant fevers.