IPA: /ˈvæst.nəs/
KK: /væstnəs/
The state or quality of being very large or extensive in size, amount, or degree.
The vastness of the ocean is both beautiful and intimidating.
Vastness → It is formed from "vast" (from Latin *vastus*, meaning empty or desolate) and "-ness" (meaning the state or quality of). The word "vastness" refers to the quality of being vast or immense in size or extent.
Think of the word 'vast' meaning empty or immense, and remember that 'vastness' describes the quality of being immense.