Think of a line drawn in a record book rather than of two people in love. Wedlock is the married state seen from outside, the way a law or a register sees it: you are either inside that line or outside it. That is why the word feels cool and official, and why the expression built on it, born out of wedlock, is simply about which side of the line someone stood on at a particular moment.
From the word’s history
From Old English wedlac, later Middle English wedlok, formed from wed, to pledge or marry, plus the old noun ending -lock. The ending is not the lock you open; it is an Old English suffix used to make nouns. The word therefore names the standing that follows a pledge, which is exactly the line in the register.
來自古英文 wedlāc，中古英文寫作 wedlok，由 wed（立誓、成婚）加上古英文的名詞字尾 -lock 組成。這個 -lock 跟今天的「鎖」不是同一件事，它是古英文用來造名詞的字尾。所以這個字指的是「立下婚約之後的那個身分」，正好就是登記簿上那條線。
Wiktionary entry for wedlock, supplied in this evidence packet (kaikki:3f6f69a190036ae4:842466970): from Old English wedlac, by surface analysis wed + -lock.
登入就可以看每一支怎麼連回核心畫面。