aporia /a-pōˈri-a or -pöˈ/

1. A professed doubt of what to say or to choose (rhetoric)
2. A difficulty

• electron probes
• electron ring accelerator
• electron ring accelerators
• electrons
• electron shell
• electron shells
• electron telescope
• electron telescopes
• electron tube
• electron tubes
• electronvolt
• electronvolts
• electronystagmography
• electro-optic
• electro-optical
• electro-optical effect
• electro-optics
• electro-osmosis
• electro-osmotic
• electrophile
• electrophiles
• electrophilic
• electrophoreses
• electrophoresis
• electrophoretic