回転
かいてん · kaiten · JLPT N2 · noun
rotation
🎡 回 = around + 転 = roll/turn: rolling around = rotation
回 means around or times, and 転 means roll or turn. Together 回転 describes turning around a central point. The same 回 appears in 一回 (once), where it counts occurrences.
回 — enclosure 囗 + smaller 囗 inside
回 is a pictograph of a swirling whirlpool or coiled spiral, shown as nested squares in modern form. The original meaning was 'to revolve' or 'turn around,' which extended to 'return' and 'a time/occurrence.' It also appears as a phonetic in characters like 茴 and 廻.