What is the meaning of "Hana-marriage"?

"Hana-marriage" in Japanese vocabulary refers specifically to the bride, and is a term of endearment used to refer to the groom as Hana-muko (はな むこ) and the bride as Hana-marriage (はな yome), with the requirement that both parties to the marriage wear a traditional kimono.

The dress for a woman's wedding is called a hanami kimono (花嫁衣裳), or hana-yome いしょう (はなよめいしょう) in Japanese, and a pure white gown (纯白色礼服), which is a Japanese dress with a pure white color on both the front and the back, is tailored to fit the occasion. Since ancient times, white has been a sacred color in Japan and was used for vestments. From the end of the Muromachi period to the Edogawa period, it was used as bridal wear, childbirth, funeral Edo period, birthday clothes, and even harakiri clothes.

Extended information:

The flower wedding garment originated in the Edo period as the great dress of the martial arts family. The traditional wedding in Japan is a Shinto wedding; and the flower wedding garment is a necessary dress for a Shinto wedding. There are three main types of hanamats, including the color tatami, the white mukuro, and the shinjiru (usually large shinjiru), which are mainly white or red in color.

The satori comes from the spring and fall dresses of the samurai women of the Muromachi period, which were like a coat-like robe. From the Edo period, it was slowly introduced into the homes of wealthy merchants and magnates, and gradually became popular as a wedding gown.

Baidu Encyclopedia - Flower Marriage