初一十五

chūyīshíwǔ

the first and fifteenth days of a month in the Chinese calendar (days of sacrifice offering and prayers for blessings)

Wiktionary

Entry Composition

1 初一 chūyī
  1. first day of lunar month
  2. New Year's Day
  3. first year in junior middle school
2 十五 shíwǔ
  1. fifteen
  2. 15