TDAmerican EnglishAmE old-fashioned a piece of equipment that you hold up to your mouth to make your voicelouder 手提式扩音器,喇叭筒SYN British English megaphone
Examples from the Corpus
bullhorn• I grabbed a bullhorn and yelled, in my most commandingflightattendant voice, for them to back up.• Certain sounds may seem to come out of a bullhorn.• The visible ones grow larger as the fogreflects up at them; their voices become bullhorns.• The cop is saying through his bullhorn that he wants to take the baby.