abacus /abˈə-kəs/

1. A counting frame, consisting of horizontal rods along which movable beads can be slid
2. A level tablet on the capital of a column, supporting the entablature (architecture)

• 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
• electrophoretically
• electrophorus
• electrophoruses
• electrophotographic