Chiliad — \KIL-ee-ad\
- a group of 1000.
- a period of 1000 years.
In 1811 Chernac’s Cribrum Arithmeticum was published, to the great joy of Gauss, who states that, although he had not sufficient patience for a continuous enumeration of the whole million, he often employed unoccupied quarters of an hour in counting here and there a chiliad.
— J. W. L. Glaisher, “Preliminary account of an enumeration of the primes in Burckhardt’s tables,” Proceedings of the Cambridge Philosophical Society, October 23 1876—May 17, 1880
Chiliad dervies from the Greek term for 1,000, chīlioi. It entered English in the late 1500s.