/jel"ee fish'/ , n. , pl. ( esp. collectively ) jellyfish , ( esp. referring to two or more kinds or species ) jellyfishes .
1. any of various marine coelenterates of a soft, gelatinous structure, esp. one with an umbrellalike body and long, trailing tentacles; medusa.
2. Informal. a person without strong resolve or stamina; an indecisive or weak person.
[ 1700-10; 1910-15 for def. 2; JELLY + FISH ]