You can hold one picture for this whole word: a chancellor's establishment. Picture a wide official building with flags at the door, floors of desks inside, and people working through papers for the person at the top. Each meaning can be seen as one corner of that picture — the building itself, the people at the desks, the branch of it posted in a foreign country, and the seat at the top that all the work is done for.
From the word’s history
The packet's source entry traces the word through Middle English chancelrie and Old French chancelerie to Late Latin cancellaria, and notes it is a doublet of chancery. The ending is the one English uses to name an establishment or a place of work, so the word starts life as 'the chancellor's establishment' — which is why it can still point at the building, at the staff, or at the post.
來源資料把這個字追到中古英語 chancelrie、古法語 chancelerie，再到晚期拉丁文 cancellaria，並指出它和 chancery 是雙生字。字尾正是英文用來指「某種機構或辦事處」的那一種。可以想成：這個字一開始就是「chancellor 的辦事處」，所以今天它才能同時指樓、指人、也指那個位子。
packet wiktionary etymology_text for chancellery (source_ref kaikki:3f6f69a190036ae4:1393711031)
登入就可以看每一支怎麼連回核心畫面。