Omphalotus omp·ha·lo·tus uncommon noun 1. a genus of mushrooms with a depressed disc in the cap Synonymsgenus Omphalotus Related words Word family Omphalotus illudens Broader terms fungus genus Parts Tricholomataceae Part of jack-o-lantern fungus WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.