Spinal means 'having to do with the spine' — the line of small bones running down the middle of your back, and the thick cord of nerves inside it. It is an adjective, and it lives almost entirely in medical and scientific language: spinal cord, spinal injury, spinal surgery, spinal column, a spinal tap. When an ordinary person is talking about ordinary things they say 'my back' or 'my backbone'; they say 'spinal' when a doctor is involved. One use you should know because it comes up in hospitals: 'a spinal' can be a noun, short for a spinal anaesthetic — an injection into the lower back that makes you numb from the waist down while staying awake. Many women in Taiwan have had one during a Caesarean birth. 'She had a spinal, not a general.' Be careful with the figurative side. In English, 'backbone' is the word that means courage ('he had no backbone'). 'Spinal' never does that job — you cannot say 'a spinal politician'. What does travel is 'spine' in the phrase 'sends a shiver down my spine', and the compound 'spine-chilling'. There is a small extra thing hiding in the origin. The Latin root spina meant a thorn or a prickle first, and a backbone second — because a row of vertebrae looks like a row of thorns. That is why plants have spines too, and why an unfriendly cactus and your back share a word.

脊椎的、脊髓的（醫療用語：spinal cord 脊髓、spinal injury 脊椎損傷；當名詞時指「半身麻醉」，就是剖腹產打的那種脊椎麻醉）