Bullhorn

a directional, high-powered, electrical loudspeaker or megaphone.
Contemporary Examples

Martin Luther King Was White? Blake Gopnik August 21, 2011
Street Battle Against Cops Again in Ferguson Despite Midnight Curfew Justin Glawe August 16, 2014
Use Islam to End the Iranian Regime Nazee Moinian June 23, 2009
Street Battle Against Cops Again in Ferguson Despite Midnight Curfew Justin Glawe August 16, 2014
Here’s Why We Can’t Get Jobs Alex Klein September 17, 2012
11 Politicians to Watch in 2011 Samuel P. Jacobs January 1, 2011
Egypt Protests: No Islamist Plot to Oust Mubarak Babak Dehghanpisheh January 30, 2011
March on Washington in 1963 Was Truly Militant, Despite Portrayals Jamelle Bouie August 25, 2013

Historical Examples

Sonny Rick Raphael
If at First You Don’t… John Brudy

noun
(US & Canadian) a portable loudspeaker having a built-in amplifier and microphone Also called (in Britain and certain other countries) loud-hailer

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Bull-information-systems
bull information systems company A multinational I.T. group based in Europe with 21,000 people and operations in more than 85 countries. In 1997, Bull earned revenues of over $4 billion, including over 65% outside of France, its country of origin. The company is ranked as the third largest systems integrator in Europe. (http://bull.com/). (1998-07-02)
Bull-kelp
noun any of various large brown seaweeds of Pacific and Antarctic waters

Bull--mastiff
one of an English breed of dogs having a short, fawn or brindled coat, produced by crossing the bulldog and the mastiff. noun a large powerful breed of dog with a short usually fawn or brindle coat, developed by crossing the bulldog with the mastiff
Bullmastiff
one of an English breed of dogs having a short, fawn or brindled coat, produced by crossing the bulldog and the mastiff.