spineless

Lacking courage or willpower.

Having no spines.

Lacking a spinal column; invertebrate.

Having no spine or spinal column; invertebrate.

Having no backbone, vigor, or courage; limp; weak; nerveless.

Having the backbone flexible or supple.

In ichthyology, having no fin-spines; soft-finned; anacanthine; malacopterous: as, the spineless fishes, or Anacanthini.

Having no spine, or vertebral column.

Having no thorns or barbs.