What is "nonpartisanism"

In political science, nonpartisanism is a lack of affiliation with a political party.

Some organizations claiming to be nonpartisan are truly such; others are nominally nonpartisan (for reasons of law or public perception) but closely follow the policies of a political party.

While the dictionary definition of partisan includes adherents of a party, cause, person, etc., in many cases, nonpartisan refers specifically to political party connections rather than being the strict antonym of "partisan", and an organization described as nonpartisan can have many decidedly controversial policies.