kidnapping is an act of kidnapping someone, an occasion when someone is kidnapped kidnapping victim, the recent kidnapping of a Dutch industrialist hostage a person who is the prisoner of someone who threatens to kill them if they do not get what they want The President is making every effort to obtain the release of the hostages

To kidnap someone is to take them against their will. This says nothing about the motive of the kidnapping. 'Kidnap' is a verb. A 'kidnapper' is someone who kidnapped someone else. A hostage is someone who has been kidnapped and is being used as a bargaining chip. 'Hostage' is a noun.

kidnapping means that you do not know where the person is, in a hostage situation the police always knows where the victims are, like in a bank heist.

Kidnap means to carry off by force for ransom, and hostage means a person held as a pledge until certain demands are met.