noun
month of birth; birthday month
Refers to the calendar month in which someone was born. Used in contexts like horoscopes, school year groupings, or age-related statistics.
私の誕生月は6月です。
My birth month is June.
誕生月ごとにクラスを分けます。
We divide the classes by birth month.
誕生日 means 'birthday' (the specific date), while 誕生月 means 'birth month' (the month of birth).
Compound of 誕生 (birth) and 月 (month).