Contiguousness as a noun is the state or quality of being contiguous. while Contiguity as a noun is a state in which two or more physical objects are physically touching one another or in which sections of a plane border on one another.
Part of speech: noun
Definition: The state or quality of being contiguous.
Part of speech: noun
Definition: A state in which two or more physical objects are physically touching one another or in which sections of a plane border on one another.
We hope you now know whether to use Contiguousness or Contiguity in your sentence.