You can picture self-contained as a box with the lid shut. Whatever it needs is already inside, so nothing has to be passed in from outside. A program that needs no other software, a flat with its own kitchen and bathroom, a person who seems fine on their own — the same closed line is drawn around each of them. The line is not a refusal of the outside world. It only says: what is needed is in here already.
From the word’s history
The word is simply self- plus contained. Contain goes back through Old French contenir to Latin continēre, to hold together or hold in. So the literal reading is close to the picture: it holds itself in.
這個字就是 self-（自己）＋ contained（被裝住的）。contain 經過古法文 contenir，來自拉丁文 continēre，意思是「一起握住、圍住」。所以字面讀起來，跟那個盒子的畫面幾乎是同一件事：它自己把自己圍住了。
Wiktionary entry supplied in this packet (source_ref kaikki:3f6f69a190036ae4:1251875468): 「From self- + contained」, with contain traced Latin continēre → Old French contenir → English contain.
登入就可以看每一支怎麼連回核心畫面。