dressed to the nines

Grishamの "The Partner" を読んでいます。
SHE INSISTED that Lance be allowed to sit through the appointment with her. She needed him, she said. He was quite cute in his tight denim shorts. His muscular legs were hairy and brown. The lawyer was scornful, but then, he'd seen everything.
Trudy was dressed to the nines-tight short skirt, tasteful red blouse, full complement of makeup and jewelry. She crossed her shapely legs to get the lawyer's attention. She patted Lance on the arm as he massaged her knee.
英語には "nine" を使った慣用句が多い様に思います。上に出てきた "dressed to the nines" はどの様な意味になるのでしょうか？
・Oxford English Dictionary: Dressed very elaborately.: But when we see him dressed to the nines, we hardly notice his deficiencies.
・Cambridge English Dictionary: to be wearing fashionable or formal clothes for a special occasion: Jackie went out dressed to the nines.
過去に私が取り上げた "nine" を含む慣用句は "the whole nine" と "talk nineteen to the dozen" です。