• 段階だんかい — stage, phase
• 階段かいだん — stairs
• 手段しゅだん — means, method
• 一段いちだん — one level, one step
• 上段じょうだん — upper level
• 下段げだん — lower level

段 is often used to describe ranks, levels, or steps — both literal (stairs) and figurative (strategy, skill levels). The radical 殳 (るまた) implies action or progression.

In martial arts or education, “段” is widely used to show one’s level of proficiency — such as 初段 (first rank) or 八段 (eighth rank).

彼かれは 黒帯くろおびの 三段さんだんです。
He holds a third-degree black belt.

この計画けいかくは 次つぎの 段階だんかいに 進すすみました。
This plan has moved on to the next stage.

“だん” is the only common reading and appears in many compound words related to steps, grades, or stages. It’s a high-frequency component in both academic and daily use.