The glass was opaque, making it hard to see inside.

Not able to be seen through; not transparent.
The walls were painted in an opaque color.
She wore an opaque dress to the party.
The window was covered with opaque film.
opaque material
opaque glass
opaque paint
impenetrable
cloudy
nontransparent
The artist used an opaque for the painting.

A substance that does not allow light to pass through.
The window was covered with an opaque film.
She chose an opaque material for the curtains.
The box was made of opaque plastic.
opaque glass
opaque paint
opaque material
cloudy
nontransparent
impenetrable
The glass is opaque, so you can't see inside.

Not able to be seen through; not transparent.
The curtains are opaque, blocking all the light.
She wore an opaque dress that hid her figure.
The paint is opaque, so it covers the wall completely.
opaque glass
opaque material
opaque color
impenetrable
cloudy
murky