Meaning : Weak in willpower, courage or vitality.
Synonyms : gutless, namby-pamby, wishy-washy
Meaning : Lacking a backbone or spinal column.
Example :
Worms are an example of invertebrate animals.
Synonyms : invertebrate
Having a backbone or spinal column.
Fishes and amphibians and reptiles and birds and mammals are verbetrate animals.