un ‧ an ‧ nounced /ˌʌnəˈnaʊnst◂/ BrE AmE adjective , adverb
[ Word Family: noun : ↑ announcement , ↑ announcer ; verb : ↑ announce ; adverb : ↑ unannounced ; adjective : ↑ unannounced ]
happening without anyone expecting or knowing about it:
We arrived unannounced.