A nosh-up is a big, satisfying meal — the kind where you sit down and really eat. It is informal British English, warm and a bit jokey, not a word for a restaurant menu or a school essay. Nosh on its own can mean food, or a snack; a nosh-up is the larger, sit-down version, closer to a feast. You might hear “a proper nosh-up” after a long day, or about a birthday dinner. Americans hardly use it. In Taiwan you will almost never hear it in the street; it belongs to British chat and British writing that wants a homely tone.

大餐；大吃一頓（英式口語）