M(edusa)

medusa noun
me·​du·​sa | \ mi-ˈdü-sə , -ˈdyü-, -zə\
Definition of medusa
1 capitalized [ Latin, from Greek Medousa ] : a mortal Gorgon who is slain when decapitated by Perseus
2 plural medusae\ mi-​ˈdü-​ˌsē , -​ˈdyü-​ , -​ˌzē , -​ˌsī , -​ˌzī\ also medusas [ New Latin, from Latin ] : the typically free-swimming, bell-shaped, usually sexually-reproducing, solitary or colonial form of a cnidarian (such as an obelia, box jellyfish, or sea nettle) in which nematocyst-studded tentacles arise and hang down from the margin of the nearly transparent, gelatinous bell
— see also JELLYFISH