仕上げる
しあげる · shiageru · JLPT N1 · verb-ichidan
to complete
🏁 仕 (do) + 上げる (raise up to the top) = do the work until it is lifted to completion
上げる means to raise or lift up, and as a finishing verb it means to bring something to its peak. 仕 means to do or serve. Together they mean to do a task all the way up to the top, which is finishing it.
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.