上限
shàngxiàn · HSK 7
upper limit
🧢 上 (up) + 限 (limit) = the up-limit, the cap; bonus: 'cap' = hat 🧢
上限 stacks 上 shàng (up, above) onto 限 xiàn (limit, restriction), so it literally reads as the upper bound. English 'cap' doubles as a hat, a handy verbal peg for the ceiling-on-a-value sense.
上 — horizontal line above a baseline
上 is an indicative character (指事): a short stroke placed above a longer reference line shows the concept of 'above' or 'up'. The earliest oracle-bone forms used two horizontal lines for this; the modern shape added a vertical stroke for clarity. The core meaning of 'upper, above, to ascend' has stayed stable for millennia.
限 — mound radical 阝 + 艮 (phonetic)
限 combines the 阝 (mound/hill) radical on the left with 艮 on the right, which provides the sound. The mound element suggests a boundary or barrier formed by terrain, and the character came to mean 'limit' or 'boundary' — the edge one cannot cross.