lunar calendar
阴 · 6 strokes
The traditional characters 陰 (Yin) and 陽 (Yang) were simplified to 阴 and 阳. In Chinese philosophy, the moon (月) corresponds to Yin (阴) and the sun (日) corresponds to Yang (阳).
历 · 4 strokes
Simplified form of 歷. Phonosemantic compound. 厤 represents the meaning and 力 represents the sound.