1Lunch — the midday meal; a casual, very commonly used loanword alternative to "昼食" in everyday and workplace conversation.
今日のランチ、一緒にどう？
Want to have lunch together today?
会議が長引いてランチを食べる時間がなかった。
The meeting ran long, so I didn't have time to eat lunch.
彼女は毎朝お弁当を作って、会社でランチを食べている。
She makes a boxed lunch every morning and eats it at the office.
2A (Western-style) plate lunch or lunch set — typically a one-plate meal or a fixed set menu offered by restaurants at midday, as in "ランチセット" (lunch set) or "ランチプレート" (lunch plate).
このレストランのランチは千円でコーヒーが付いてくる。
This restaurant's lunch set costs 1,000 yen and comes with coffee.
平日限定のランチメニューはお得だ。
The weekday-only lunch menu is a great deal.
オムライスのランチプレートにはサラダとスープが付いた。
The omelette-rice lunch plate came with a salad and soup.