A stanchion is a strong upright post that holds something up or keeps something in place. The key word is upright — it stands straight up, like a leg. If a bar lies across, that is not a stanchion; the stanchion is the one standing. You meet them in real places more than in conversation. On a ship, stanchions are the metal posts along the edge of the deck, with wire or rope between them, so nobody falls into the sea. In a building site, they hold up a floor. On a bicycle or a motorbike with front suspension, the stanchions are the shiny upper tubes of the fork. In a cow shed, stanchions are the frames that hold each cow gently in its own place at feeding time. In an airport or a bank, those little posts with a belt between them, making the queue snake back and forth — those posts are stanchions too, though most people just say "posts". So the word is a technical, working word. Builders, sailors, engineers and farmers use it every day; ordinary people rarely do. If you say "post" or "pole" instead, nobody will ever misunderstand you. Knowing "stanchion" is useful mainly for reading — instructions, sailing books, engineering texts, safety notices. It is a countable noun: one stanchion, two stanchions. There is also a rare verb, to stanchion something (to fix it with such posts), but you will almost never need it.

支柱、立柱、（船上的）欄杆柱。就是直立、用來撐住或擋住東西的那根柱子。這是工程、造船、工地在用的專業字，一般講話說 post 就好。