step·ping·stone 
(stĕpĭng-stōn′)
(stĕpĭng-stōn′)n.
1. A stone that provides a place to step, as in crossing a stream.
2. An advantageous position for advancement toward a goal.
- electrogenesis
- electrogenic
- electrograph
- electrohydraulic
- electrohydraulically
- electrojet
- electrokinetics
- electroless plating
- electrologist
- electroluminescence
- electroluminescent
- electrolysis
- electrolyte
- electrolytic
- electrolytically
- electrolytic capacitor
- electrolytic cell
- electrolyze
- electromagnet
- electromagnetic
- electromagnetically
- electromagnetic bomb
- electromagnetic field
- electromagnetic force
- electromagnetic interaction