Main Entry: lu·na·tion

Pronunciation: \lü-ˈnā-shən\

Function: noun

Etymology: Middle English lunacioun, from Anglo-French lunaison, from Medieval Latin lunation-, lunatio, from Latin luna

Date: 14th century

: the period of time averaging 29 days, 12 hours, 44 minutes, and 2.8 seconds elapsing between two successive new moons