Worryingly is an adverb, and it does a job that beginners rarely need but writers use constantly: it comments on the whole sentence rather than on one verb. Put it at the front — 'Worryingly, no one has heard from him since Tuesday' — and it means 'and this is the part that makes us anxious'. The speaker is stepping outside the facts for a moment to tell you how to feel about them. Compare 'Sadly, he lost' or 'Strangely, the door was open'; same move. Its other use is before an adjective, where it means 'to a degree that causes concern': worryingly thin, worryingly quiet, worryingly high. 'Her hands were worryingly cold.' This is a favourite of news reporting and of anyone writing carefully — it flags concern without shouting. It is far commoner in British English than American, and it belongs to writing and to careful speech more than to chat with friends. Built simply: worry → worrying (the adjective describing something that causes anxiety) → worryingly, with -ly, the ending that makes adverbs.

令人擔憂地；用在句首時等於「令人擔心的是…」。也可放在形容詞前面，表示程度嚴重到令人不安，例如 worryingly thin（瘦得令人擔心）。書面語，英式英文尤其常用。