The Oxford Thesaurus An A-Z Dictionary of Synonyms - spineless adj.

1) Technical invertebrate: There are more species of spineless creatures than those with internal backbones. 2) weak, feeble, flabby, irresolute, weak-willed, indecisive, ineffectual, ineffective, impotent, powerless: After her reign, any king would appear spineless. 3) cowardly, dastardly, pusillanimous, timorous, lily-livered, white-livered, craven, fearful, timid, spiritless, squeamish, Colloq yellow, chicken-hearted, chicken, yellow-bellied, wimpish: She said you were spineless because you refused to go into the lions' cage.