GETSU, GATSI 
tsuki 
(名) the moon (名) a month
man'getsu (名) a full moon.
san'gatsu (名) March
toshitsuki (名) many years and months.
maigetsu (名) every month

Links: KanjiDic: EDict : Wikimedia
Etymologies: 中文字譜 : 説文解字