chiliaëdron

In a Man who ſpeaks of a Chiliaëdron, or a Body of a thouſand ſides, the Idea of the Figure may be very confuſed, though that of the Number be very diſtinct; ſo that he being able to diſcourſe, and demonſtrate concerning that part of his complex Idea, which depends upon the Number of a Thouſand, he is apt to think, he has a diſtinct Idea of a Chiliaëdron; though it be plain, he has no preciſe Idea of its Figure, ſo as to diſtinguiſh it, by that, from one that has but 999 ſides.

1689–1700, John Locke, An Eſſay Concerning Humane Underſtanding (fourth edition, 1700), book II, chapter xxix, § 13, page 204