spineless

If you're spineless, you're weak or cowardly — or both. It would be spineless to watch a bully pick on someone much smaller and not try to intervene.

You can certainly use this adjective to literally mean "lacking a spine," and you might if you're talking about invertebrates like the spineless forest lizard or the Garo spineless eel. It's more common to call people spineless as a derogatory way of commenting on their weakness. A spineless superhero is too scared to confront the bad guys, and a spineless politician avoids conversation with critical constituents.

Definitions of spineless
1

adj weak in willpower, courage or vitality

Synonyms:
gutless, namby-pamby, wishy-washy
weak
wanting in physical strength

adj lacking spiny processes

spineless fins”
Antonyms:
spinous, spiny
having spines

adj lacking a backbone or spinal column

Synonyms:
invertebrate
Antonyms:
vertebrate
having a backbone or spinal column

adj lacking thorns

Synonyms:
thornless
unarmed
(used of plants or animals) lacking barbs or stings or thorns

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