Picture a hand going into a bag of something and coming out again, while the person keeps talking. No table, no plate, no set amount, and nobody has decided when it ends. That easy, eating is what the word is built on. From there it goes two ways: the doing of it, and the stuff being eaten. The word is friendly all the way through, so wherever it turns up, the setting is relaxed.
nosh 的核心畫面可以想成：一隻手伸進袋子裡拿東西，拿出來吃，嘴巴還在講話。沒有餐桌、沒有盤子、沒有算份量，也沒有人說什麼時候算吃完。整個字就是從這種「隨便吃一點」長出來的。接著它往兩邊走：一邊是這個動作，一邊是被吃的東西。不管走到哪一邊，語氣都是輕鬆的，所以它出現的場合一定很隨性。
From the word’s history
Wiktionary traces nosh to Yiddish nashn, to nibble, and further back to Middle High German naschen with the same sense. Nibbling is exactly the picture the modern word still carries.
Wiktionary 記的來源是意第緒語 נאַשן（nashn，小口吃、吃零嘴），再往前是中古高地德語的 naschen（nibble）。「小口啃一點」正好就是這個字今天還帶著的畫面，所以核心放在「吃」這個動作上。
Wiktionary, "nosh" (etymology 1)
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