What does haute couture mean in fashion?

In fashion, “haute couture” means "high sewing" or "high dressmaking." Haute couture is French and refers to the creation of one-of-a-kind pieces by an esteemed fashion designer or house for a particular client. 

Haute couture garments such as dresses are pieces of clothing constructed by hand from start to finish and are made with the highest quality materials. They are expertly created by firms that are official member organizations of the Fédération de la Haute Couture et de la Mode (FHCM), which is the governing body in France that regulates this segment of the fashion industry. Dior, Maison Margiela and Schiaparelli are some of fashion's universally revered haute couture houses.