1. To deceive by trickery
2. To fool or to cheat
‘Dupe’ sounds like the word ‘Dope’ which means to make something impure, this can be related to the word ‘dupe’ as it would mean to cheat someone.
1. The man in the hotel tried to dupe her friend into paying a high price for a cheap watch.
2. We were duped into thinking the dummy was a real alien.