• 円柱えんちゅう — cylindrical column
• 支柱しちゅう — support post
• 角柱かくちゅう — rectangular prism
• 鉄柱てっちゅう — iron pillar
• 大黒柱だいこくばしら — mainstay, family breadwinner
• 茶柱ちゃばしら — tea stalk (floating upright)

The character 柱 combines 木 (tree/wood) with 主 (main, master), suggesting a main piece of wood — a central support post. It often appears in construction-related words, as well as metaphorical contexts for leadership or foundation.