What do the following names and words have in common?

Exodus
Venus
Area
Indigo
Nobility

HINTS:
Silver and John Adams could be added to the list.

Answers:

They are all second on a well-known list:

Exodus - Second book of the Old Testament 
Venus - Second planet from the sun
Area - Second dimension
Indigo - Second color of the rainbow
Nobility - Second estate
(Silver - Second highest medal in the Olympics)
(John Adams - Second President of the United States)