street oratory; soapbox speech; stump speech
Refers to giving a speech in a public outdoor space, often to gather support or promote a cause. The term is neutral but often associated with political campaigning or activism.
Before the election, the candidate gave a street speech in front of the station.
When he was young, he often gave soapbox speeches in the park.
演説 is a general term for a formal speech or address, while 大道演説 specifically refers to an outdoor public speech, often impromptu or on a street corner.
街頭演説 is a near-synonym also meaning street speech, but 大道演説 can carry a slightly more old-fashioned or dramatic nuance, evoking the image of a soapbox orator.
Compound of 大道 (main street, public road) and 演説 (speech, address). The term likely emerged in the Meiji or Taisho era when public political speeches on streets became common.