immense extent or expanse; immensity
"The view from the mountain revealed an immense stretch of forest stretching to the horizon."
"There is no single grammatical way to use immense as a noun because in standard English grammar, it functions exclusively as an adjective modifying nouns like scale or size. You cannot say something such as "the immense," and therefore there are no natural example sentences for the word used in that part of speech."
unusually great in size or amount or degree or especially extent or scope
"huge government spending"
"huge country estates"
"huge popular demand for higher education"
"a huge wave"
"the Los Angeles aqueduct winds like an immense snake along the base of the mountains"
"immense numbers of birds"
"at vast (or immense) expense"
"the vast reaches of outer space"
"the vast accumulation of knowledge...which we call civilization"
Huge, gigantic, very large.
"The immense canyon stretched endlessly before us, dwarfing everything around it."
In plain English: Immense means extremely large, so big that it is hard to imagine how much space something takes up.
"The crowd gathered in immense numbers to welcome their favorite celebrity home."
The word immense comes from the Latin phrase in-mensus, which literally means "unmeasurable." It entered English through Middle English and Old French to describe something so vast that it cannot be measured or counted.