jellyfish (n.)

• baby
• chicken
• coward
• crybaby
• doormat
• fence-sitter
• funk
• invertebrate
• lightweight
• milksop
• mollycoddle
• mouse
• mugwump
• namby-pamby
• nebbish
• nonentity
• pansy
• pantywaist
• pushover
• sissy
• softy
• sop
• waverer
• weakling
• wobbler