會吸東西的那張紙
這一組是字面：同一種吸水紙，只是吸的液體不同。
noun · C1
A large sheet of soft, thick paper kept flat on top of a desk, which soaks up ink that spills or has not dried yet, and protects the desk underneath.
桌上的吸墨紙墊
核心畫面
One way to hold this word: a sheet of soft paper that drinks. Put something wet on it and the paper takes it in and keeps it — the ink stays in the paper instead of running across the desk. That is the whole trick, and the word follows the trick rather than any one object. Change the liquid and the same paper does the same job under a new name: ink on a desk, perfume at a shop counter, a drug in liquid form. And because that sheet lay in the middle of every working desk, the running record kept beside it on the counter took the name too.
blotter 可以想成一張會喝東西的軟紙。把濕的東西放上去，紙就把它吸進去、留住——墨水停在紙裡，不會在桌面上流開…更多收起
blotter 可以想成一張會喝東西的軟紙。把濕的東西放上去，紙就把它吸進去、留住——墨水停在紙裡，不會在桌面上流開。這個字跟著的是這個動作，不是某一樣特定的東西。換一種液體，同一張紙換個名字做同一件事：桌上吸墨水，櫃檯上吸香水，也可以吸藥水。而因為這張紙就攤在每張辦公桌的正中間，旁邊那本隨手記的簿子，後來也一起沿用了這個名字。From the word’s history
Wiktionary gives the make-up of the word directly: blot plus -er, the ending that names the thing that does something. So the word literally says 'the thing that blots' — the thing that takes up a wet mark — which is exactly the picture every sense still uses.
依 Wiktionary，這個字的組成很直接：blot（墨漬、吸掉墨水）加上 -er（做這件事的東西）。字面上就是「負責吸掉墨漬的那個東西」。這正好就是每個意思底下都還在用的那張畫面。
Wiktionary (kaikki:3f6f69a190036ae4:917704631): From blot + -er.
Three branches
那張紙旁邊的簿子
這一支不是靠吸水，而是靠位置：值班台上那張紙旁邊，就是隨手記事情的地方。這是一條理解的線索，不是已證實的來源。
noun · C1
A book or list in which an organization writes down each day's events in the order they happen, with the time and a short note for each one. In American English the best known is the police blotter, the daily record of arrests and calls, and banks and trading desks keep their own blotters too.
逐日流水帳簿；值日紀錄簿
吸了藥水的小紙片
回到核心的吸水畫面，只是液體換成了藥水，而紙把自己的名字給了藥。
noun · C2
An informal American name for the illegal drug LSD, which is often soaked into absorbent paper and sold as small printed squares. The word is uncountable in this use, and the paper itself is sometimes called blotter acid.
（美式俗稱）迷幻藥 LSD