The word contraband, reported in English since 1529, from Medieval French contrebande "a smuggling," denotes any item which, relating to its nature, is illegal to be possessed or sold.

Used for goods that by their nature, e.g. too dangerous or offensive in the eyes of the legislator (those are termed contraband in se) are forbidden, and for so-called derivative contrabande, i.e. goods that may normally be owned but are liable to be seized because they were used in committing an unlawful act and hence begot illegally, such as:

• Smuggling
  Smuggling
  Smuggling is the clandestine transportation of goods or persons, such as out of a building, into a prison, or across an international border, in violation of applicable laws or other regulations.There are various motivations to smuggle...
  
   goods
• stolen goods – knowingly participating in their trade is an offense in itself, called fencing
  Fence (criminal)
  A fence is an individual who knowingly buys stolen property for later resale, sometimes in a legitimate market. The fence thus acts as a middleman between thieves and the eventual buyers of stolen goods who may or may not be aware that the goods are stolen. As a verb, the word describes the...
  
  
• the fruits of fraud
  Fraud
  In criminal law, a fraud is an intentional deception made for personal gain or to damage another individual; the related adjective is fraudulent. The specific legal definition varies by legal jurisdiction. Fraud is a crime, and also a civil law violation...
  
  , forgery
  Forgery
  Forgery is the process of making, adapting, or imitating objects, statistics, or documents with the intent to deceive. Copies, studio replicas, and reproductions are not considered forgeries, though they may later become forgeries through knowing and willful misrepresentations. Forging money or...
  
   etc.

The word is also used as an adjective, again meaning 'distributed or sold illicitly'.

In international law

International law

Public international law concerns the structure and conduct of sovereign states; analogous entities, such as the Holy See; and intergovernmental organizations. To a lesser degree, international law also may affect multinational corporations and individuals, an impact increasingly evolving beyond...

, contraband is enemy goods carried by vessels of neutral nations during wartime that may be confiscated by a belligerent

Belligerent

A belligerent is an individual, group, country or other entity which acts in a hostile manner, such as engaging in combat. Belligerent comes from Latin, literally meaning "to wage war"...

 power and thus prohibited from delivery to the enemy.