reference

As a noun sign

is (sometimes|also used uncountably) a visible indication.

As a verb sign

is to make a mark.

As a noun footnotes is

.

As a verb footnotes is

(footnote).

As a noun individual is

a person considered alone, rather than as belonging to a group of people.

As an adjective individual is

relating to a single person or thing as opposed to more than one.

As a verb bases

is .

As a noun substitution is

substitution, replacement.

As a noun indifference

is indifference, uncaringness.