A jellyfish is a type of sea creature with a soft, squishy body and stinging tentacles. These creatures float around in the ocean.
You might hear people talk about seeing jellyfish on vacation at the beach or on a snorkeling trip. If you're swimming near a coral reef, it's not uncommon to see them drifting lazily by, their long tentacles waving gently in the current. Jellyfish stings can be painful, so it's usually best to keep a safe distance from these creatures. Some beaches have warning signs about jellyfish in the water, especially after big storms that bring lots of marine life into shallow waters.
An almost transparent aquatic animal; any one of the acalephs, especially one of the larger species, having a jellylike appearance.
