jem ‧ my /ˈdʒemi/ BrE AmE ( plural jemmies ) British English , jimmy ( plural jimmies ) American English noun [countable]
[ Date: 1800-1900 ; Origin: From the man's name Jemmy , from James ]
a short strong metal bar used especially by thieves to break open locked doors, windows etc
—jemmy verb [transitive]