a long piece of cloth with a message on it that is carried between two poles or hung in a public place to show support for something 横幅；旗幡 
A huge banner over the street said ‘Welcome home’. 街道上方的一面巨幅横幅上写着“欢迎回家”。 Protesters carried a banner reading ‘Save our Wildlife’. 抗议者打着 “救救我们的野生生物” 字样的横幅。
Extra ExamplesBanners demanded the leader's resignation. 横幅上写着要求总统辞职。 The demonstrators carried banners bearing various slogans. 示威者打着写有各种标语的横幅。 They marched forward with banners waving in the wind. 他们举着迎风飘扬的旗帜前进。 A banner strung across the road read, ‘Welcome home, boys!’ 一面横幅横跨马路，上面写 ：“欢迎回家，小伙子们！”
Oxford Collocations Dictionaryverb + banner- drape
- hang
- hang out
- …
- hang
- flutter
- fly
- …
- ad
- headline
- year
- …
Word OriginMiddle English: from Old French baniere, ultimately of Germanic origin and related to band ‘musical group’.
Idioms
under the banner (of something)