A somewhat formal or literary term for the midday meal; in everyday speech, 昼ご飯 (ひるごはん) or 昼食 (ちゅうしょく) are more common.
Let's have lunch after the meeting.
He always looks forward to lunchtime.
Compound of 中 (ちゅう, 'middle, midday') and 飯 (はん, 'meal'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the midday meal.