Etymology

Proper noun

1. A huge fictional demonic humanoid being with the head of an octopus and bat wings, around whom an insane cult developed.
   • 1926 — H.P. Lovecraft, The Call of Cthulhu

     Then, bolder than the storied Cyclops, great Cthulhu slid greasily into the water and began to pursue with vast wave-raising strokes of cosmic potency.

Adjective

1. Pertaining to the mythos of Cthulhu and additional otherworldly beings created by H. P. Lovecraft or inspired by his writings and imitators.