上司
じょうし · joushi · JLPT N3 · noun
superior
👔 上 (above) + 司 (official, in charge) = the official above you
上 means up or above. 司 means to be in charge, as in 司会 (MC) and 司令 (commander). So your 上司 is the person in charge one level above you: your boss. Note that the reading is じょうし, not うえし.
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.