noun
A designated day off that is not part of regular holidays, often granted by an employer or institution for a specific reason.
会社の創立記念日は特別休日として扱われる。
The company's founding anniversary is treated as a special holiday.
今年は特別休日が増えて、連休が長くなった。
This year, special holidays increased, making the consecutive holidays longer.
Compound of 特別 (special) and 休日 (holiday). The exact historical derivation is uncertain, but the word is transparently formed from its components.