There are more words: increase your search size (the gear button) or decrease the word length above.
You can also try words with the phrase IRK, words starting with the letters IRK, or words ending in the letters IRK.
Words… ending with q, starting with q, starting with qa, starting with qo, with two letters, starting with x, starting with j, ending with j,
Some random searches:
MTAKPZ, ZBPKI, VKXE, BLREP, PPVCVY, HNAK,