brief
She was forced to appear live on television, completely unbriefed, and she performed brilliantly.
Unbriefed and without having done any research, they arranged a meeting with the country's president.
By now, the unbriefed reader will be wondering what there is in this agreeable novel that should so enrage the author's critics.

SMART Vocabulary: related words and phrases

Information and messages
advance notice
advance warning
advertisement
aide-mémoire
ammunition
bumper sticker
credential
flier
gory
guideline
handout
info
PSA
push notification
radiogram
readout
subtlety
telemetry
the gory detailsidiom
the real deal

You can also find related words, phrases, and synonyms in the topics:

Instructions and orders