Its source is Yaakov, a Hebrew name meaning "One who grasps by the heel or supplanter."
This boy's name is used in Czech.
In the Jewish scriptures, Jacob was the youngest son of Isaac and Rebecca.
With his mother's help, Jacob tricked Isaac into giving him the blessing (and the inheritance that went with it) to which his elder brother Esau was entitled. In his rage, Esau cried ''Is he not rightly called Jacob? For he has supplanted me.''