Several hands dropping a share each into the same bucket. What comes out belongs to all of them: no single share decides it, but take one away and the result changes.
可以想成好幾隻手，各自往同一個桶子裡丟進一份東西。最後桶子裡的結果是大家湊出來的：沒有哪一份說了算，可是少了一份，結果就不一樣。contributory 的兩個用法都從這個畫面長出來——一邊丟進去的是「原因」，一邊丟進去的是「錢」。
From the word’s history
The word is built from con- (together) and the tribute family (a share handed over). Together: each side hands over a share.
這個字可以拆成 con-（一起）和 tribute 那一族的「交出去的一份」。合起來就是「各出一份，一起湊」。這正好說明它為什麼總帶著「之一」的味道。
Wiktionary entry supplied in this batch's evidence packet (source_ref kaikki:3f6f69a190036ae4:1413698669): from earlier contributary, from Middle English contributarie, from con- + tributarie after Middle French contributaire.
登入就可以看每一支怎麼連回核心畫面。