The term 'Lunar Stage' refers to the different phases of the moon. The five-letter word 'PHASE' is an appropriate answer for this crossword, as it describes the various stages of the moon's cycle. The moon goes through eight distinct phases, including new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, and waning crescent. Each PHASE lasts for a certain amount of time, and the cycle repeats itself every 29.5 days.