"vast window" is correct and usable in written English.
You can use it to describe large windows, typically in a grand, impressive building. For example, "The mayor's office has a vast window overlooking the city skyline."
And as at Nomiya, the dining room's vast window offers a remarkable view.
What a stunner: soaring columns, a spiralling staircase and, through the vast window, Manhattan's dimly glimmering skyline (design by Christopher Oram).
Large, calm and elegant, with its vast window space filtered by pearl-rope curtains, it opens onto a balcony that faces over Lincoln Center's plaza.
We first meet her in a tipsily decorated artist's studio in Paris, flitting between a red leather Chesterfield splattered with paint and a vast window.
A vast window by Richter was installed last year in the south transept of the Cologne Cathedral, a Gothic bastion of Roman Catholicism in northern Europe, which was begun in 1248 and finally completed in 1880 (when it became, for four years, the world's tallest building).
As Mr. Shaoul walked back to his car, he stopped to wave at his almost-2-year-old twins, who stood behind the vast window of the apartment Mr. Shaoul and his family are occupying while he renovates their West Village townhouse; their view is of the Arman, which he visits daily.
In spring and summer, the protected plants or trees were normally wheeled out through the vast window-wall to be tastefully arranged in an ornamental garden.
Sitting rooms and bedrooms are orientated on vast windows that frame the natural beauty outside.
The view out of its vast windows offers incomparable people-watching opportunities.
Vast windows overlook a sheer drop to the crater floor and a panorama that stretches forever.
I can see white condo towers and water views from the vast windows.
