unannounced

/ˌʌnəˈnaʊnst/
adjective
  1. Happening without any warning or notice; not previously told about.
    • My aunt made an unannounced visit last night.
    • The company conducted an unannounced inspection of the factory.
    • The fire drill was unannounced, so everyone was surprised.
Antonyms
What does "unannounced" mean? | whatsthatwordmean | whatsthatwordmean