1. Plural of pentode; vacuum tubes or electronic devices with five electrodes (cathode, anode, and three grids), used in amplification and signal processing.
Usage: technical; electronics

Examples

• The vintage radio used pentodes to amplify the incoming signal.
• Engineers selected pentodes for their superior gain and stability in the amplifier circuit.
• Pentodes were common in mid-20th-century audio equipment before transistors became widespread.
• The audio enthusiast restored the old amplifier by replacing worn pentodes with new ones.
• Pentodes offer better performance than triodes in many high-frequency applications.