Racehorse Names Are Limited to This No. of Letters

This page is the CodyCross answer for the clue below from London, Group 497, Puzzle 3 (Changing of the Guard).

Question is: Racehorse Names Are Limited to This No. of Letters

and the answer is: EIGHTEEN

Word Meaning:

EIGHTEEN — The cardinal number occurring after seventeen and before nineteen, represented in Roman numerals as XVIII and in Arabic numerals as 18.

Definitions from Wiktionary.