Idiotic Paper Size of 13½ X 17 Inches?

This page is the CodyCross answer for the clue below from Treasure Island, Group 1034, Puzzle 2 (Lady Mary Killigrew).

Question is: Idiotic Paper Size of 13½ X 17 Inches?

and the answer is: FOOLSCAP

Word Meaning:

FOOLSCAP — (strictly) Writing paper sheets measuring 13.25 × 16.5 inches.

Definitions from Wiktionary.