Definition of megaphonic in US English:

megaphonic

adjective

  • See megaphone

    • ‘You pointed that out to the chief Government whip who was calling out in a voice that could only be described as ‘megaphonic’, right across the House.’
    • ‘The playback utilized a unit quite similar to the recording device, in which the cylinder or disk was spun, which vibrated a needle which vibrated a diaphragm which was amplified by an acoustic megaphonic horn.’
    • ‘After the chorus, the megaphonic vocals return.’
    • ‘Increased engine performance can be derived by arching the plate within the exhaust chamber to approximate a megaphonic area reduction within the exhaust chamber.’

Pronunciation

megaphonic

/ˌmeɡəˈfänik/