unannounced
adj. 突然的；未经宣布的；未通知的
例句
She just turned up unannounced on my doorstep.
她未打招呼就来到我家门口了。
《牛津词典》
He had just arrived unannounced from South America.
他刚从南美来，事先也没通知。
《柯林斯英汉双解大词典》
Much to the shock of everyone, Palmer comes unannounced to CTU.
很多反恐组的工作人员大吃一惊，帕默竟然没有打招呼就来到了反恐组。
