1 An example of foil is aluminum foil, a thin metal sheet used to cover food before you put it in the freezer. 2  An example of foil is a long, thin sword used in sword fighting.
http://www.yourdictionary.com/foil
In fiction, a foil is a character who contrasts with another character (usually the protagonist) in order to highlight particular qualities of the other character. In some cases, a subplot can be used as a foil to the main plot. This is especially true in the case of metafiction and the  story within a story  motif. The word foil comes from the old practice of backing gems with foil in order to make them shine more brightly.
https://en.wikipedia.org/wiki/Foil_(literature)
The legislature hereby finds that a free society is maintained when government is responsive and responsible to the public, and when the public is aware of governmental actions. The more open a government is with its citizenry, the greater the understanding and participation of the public in government.
http://www.dos.ny.gov/coog/foil2.html
The people's right to know the process of governmental decision-making and to review the documents and statistics leading to determinations is basic to our society. Access to such information should not be thwarted by shrouding it with the cloak of secrecy or confidentiality.
http://www.dos.ny.gov/coog/foil2.html
A foil usually either differs dramatically or is extremely similar but with a key difference setting them apart. The concept of a foil is also more widely applied to any comparison that is made to contrast a difference between two things.
https://en.wikipedia.org/wiki/Foil_(literature)
Origin of foil. 1  Archaic the scent or trail of an animal. 2  Archaic a thwarting. 3  a leaflike, rounded space or design between cusps or in windows, etc., as in Gothic architecture. 4  a very thin sheet or leaf of metal; specif., such a sheet, as of aluminum, used for wrapping food, etc.
http://www.yourdictionary.com/foil
The legislature therefore declares that government is the public's business and that the public, individually and collectively and represented by a free press, should have access to the records of government in accordance with the provisions of this article. §85.
http://www.dos.ny.gov/coog/foil2.html
By this definition, Batman and joker are the perfect example of what a foil is, in all aspects of the word.
http://literary-devices.com/content/foil
Foil wrapped food on a grill. Foil wrapped food on a grill. Foil is defined as a thin piece of metal, or a sword used in fencing. 1  An example of foil is aluminum foil, a thin metal sheet used to cover food before you put it in the freezer. 2  An example of foil is a long, thin sword used in sword fighting.
http://www.yourdictionary.com/foil
If any provision of this article or the application thereof to any person or circumstances is adjudged invalid by a court of competent jurisdiction, such judgment shall not affect or impair the validity of the other provisions of the article or the application thereof to other persons and circumstances.
http://www.dos.ny.gov/coog/foil2.html
what is a foil
A foil is the scent or trail of an animal. A foil is a archaic the scent or trail of an animal.