pantywaist (n.)

• baby
• chicken
• crybaby
• doormat
• goody-goody
• invertebrate
• jellyfish
• lightweight
• lily
• milksop
• mollycoddle
• namby-pamby
• nance
• nancy
• nebbish
• nonentity
• pansy
• pushover
• sissy
• softy
• sop
• weakling