The standard word for the midday meal, used in both casual and formal contexts.
昼食はいつも12時に食べます。
I always eat lunch at 12 o'clock.
今日の昼食は何にしますか。
What shall we have for lunch today?
She has lunch at the company cafeteria every day.
I finished lunch before the meeting.
I ate a sandwich for lunch.
Lunchtime is from noon to one o'clock.
lunch time