noun
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.
noun
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'.
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'.