noun
black crested garment
Refers to formal Japanese clothing, typically a kimono or haori, dyed black and bearing a family crest (紋). Most commonly associated with men's formal wear such as the montsuki haori hakama set.
結婚式では、新郎の父親は黒紋付を着ることが多い。
At weddings, the groom's father often wears a black crested garment.
紋付 is a general term for a crested garment, while 黒紋付 specifies the black version, which is the most formal and common type.
Compound of 黒 (black) + 紋 (crest) + 付き (attached). The spelling 黒紋付 is a standard abbreviation of 黒紋付き.