首sau2日jat6封fung1

English

1. first day cover (philately)
2. (of philately) first day cover

粵語 — Cantonese

1. 新郵票發行嘅第一日，將郵票貼喺特製信封右上角，加埋當日郵政日戳或特別紀念郵戳嘅信封（量詞：個）

Examples

• 我好鍾意收集首日封，因為我覺得好有紀念價值。

  I love to collect first day covers, as I believe that they've got sentimental value.