visibility

As a noun visibility

is (uncountable) the condition of being visible.

As an adjective undefined is

lacking a definition or value.

In uncountable|lang=en terms the difference between observability and visibility

is that observability is (uncountable) the state of being observable while visibility is (uncountable) the condition of being visible.

In countable|lang=en terms the difference between observability and visibility

is that observability is (countable) a measure of the extent to which something is observable while visibility is (countable) the degree to which things may be seen.

As nouns the difference between observability and visibility

is that observability is (uncountable) the state of being observable while visibility is (uncountable) the condition of being visible.

As nouns the difference between visibility and perceptibility

is that visibility is (uncountable) the condition of being visible while perceptibility is the state, quality, or condition of being perceptible.

As nouns the difference between perception and visibility

is that perception is organization, identification, and interpretation of sensory information while visibility is (uncountable) the condition of being visible.

As nouns the difference between visibility and responsibility

is that visibility is (uncountable) the condition of being visible while responsibility is the state of being responsible, accountable, or answerable.

As nouns the difference between existence and visibility

is that existence is the state of being, existing, or occurring; beinghood while visibility is (uncountable) the condition of being visible.

As nouns the difference between visibility and presence

is that visibility is the condition of being visible while presence is the fact or condition of being present, or of being within sight or call, or at hand.

As a verb presence is

to make or become present.

As nouns the difference between visibility and null

is that visibility is the condition of being visible while null is a non-existent or empty value or set of values.

As an adjective null is

having no validity, "null and void.

As a verb null is

to nullify; to annul.

In uncountable terms the difference between feasibility and visibility

is that feasibility is the state of being feasible or possible while visibility is the condition of being visible.

As nouns the difference between visibility and view

is that visibility is the condition of being visible while view is visual perception.

As a verb view is

to look at.