kidnapper vs shanghaier

kidnapper and shanghaier both are nouns.

Word	Noun	Adjective	Verb	Adverb
kidnapper	Yes	No	No	No
shanghaier	Yes	No	No	No

As nouns, shanghaier is a hyponym of kidnapper; that is, shanghaier is a word with a more specific, narrower meaning than kidnapper:

kidnapper: someone who unlawfully seizes and detains a victim (usually for ransom)
shanghaier: a kidnapper who drugs men and takes them for compulsory service aboard a ship

Other hyponyms of kidnapper include crimp, crimper, seizer.

kidnapper (noun)	shanghaier (noun)
someone who unlawfully seizes and detains a victim (usually for ransom)	a kidnapper who drugs men and takes them for compulsory service aboard a ship