Word History: Kidnapper seems to have originated among those who perpetrate this crime. We know this because kid and napper, the two parts of the compound, were slang of the sort that criminals used. Kid, which still has an informal air, was considered low slang when kidnapper was formed, and napper is obsolete slang for a thief, coming from the verb nap, "to steal." Nap is possibly a variant of nab, which also still has a slangy ring. In the second half of the 1600s, when the word kidnapper begins to appear in English, kidnappers plied their trade to secure laborers for plantations in colonies such as the ones in North America. The term later took on the broader sense that it has today. The verb kidnap begins to be attested a bit later than kidnapper and is possibly a back-formation from kidnapper—that is, the suffix -er was removed from kidnapper to create a new verb kidnap.