jockey's racing uniform
Specific term for the colorful uniform worn by jockeys during horse races, often bearing the owner's colors.
彼の勝負服は赤と白のストライプだ。
His racing uniform is red and white stripes.
best clothes; dress to impress; power outfit
Colloquial, especially among women, for an outfit saved for important occasions like dates or meetings, akin to 'lucky outfit' or 'armor'.
今日は大事なプレゼンだから、勝負服で行く。
I have an important presentation today, so I'm wearing my best outfit.
デートの日はいつも勝負服を着ていく。
On date days, I always wear my lucky outfit.
Compound of 勝負 (shōbu, 'match, contest') and 服 (fuku, 'clothes'). Originally referred to a jockey's uniform worn during races, later extended colloquially to mean clothes worn for important personal 'battles'.