Today’s entry will also contain a little about cross-lingual coincidence (what?).
The word for today is “shigoto”, which describes the job of a person. Taking a look at the kanji, one part of the etymology should immediately become clear. The latter part “goto”, is clearly a voiced version of “koto”, being a general word for “(conceptual) thing.” The word “koto” alone probably deserves an article of its own, or rather a book, so I won’t discuss that for now.
The former part “shi”, however, is not as readily recognized. The kanji 仕 doesn’t really offer any help here. Its literal meaning would be “serve (as a servant &c.)” and that hardly has anything to do with “job.” Well, perhaps you could think the origin of this word would literally be “slave-thing”; and “work” is the main thing slaves do.
Yet, this explanation doesn’t really account for the actual pronunciation “shi”, which is only the Sino-Japanese reading. The Japanese reading would be “tsukaeru” (“serve”) and we would expect 仕事 to be pronounced “*tsukaegoto”, if that explanation were true. All in all, this doesn’t seem very likely.
So, we can ignore the kanji once again. The correct etymology turns out to be that “shi” is derived from the verb 為る(suru), “do.” Literally, “shigoto” just means “(a) doing.”
Incidentally, the German word is quite similar in that respect. One word for “job” in German is “Tätigkeit” (“do-itivity”). It is derived from nominalization of the the verb “do”, just as its Japanese counterpart. This is what I meant by “cross-lingual coincidence” (coincidence as in “be coincident”). The actual vocabulary and the phonology is completely different, but the underlying concept, how reality is framed, remains the same. There’s a great book by Steven Pinker where this idea gets discussed in detail. I can only recommend you read it if you’re interesting in this stuff, it’s great and well-written.
The English word “activity” has got the same origin, albeit it isn’t specifically reserved for a specific activity (“job”).
Lastly, using a Chinese character only for its sound to represent a word, irrespective of its actual meaning, is called ateji. 仕 is a character you will see used again in other compounds for the 連用-form of the verb “suru” (“do”). Just to give a few examples: 仕草,仕組み,仕切れ,仕業.
May you have fun at “doing.”