Unfortunately means sadly or regrettably, used when something disappointing or unwanted happens. When you say “Unfortunately, it rained on our field trip,” you're expressing that the rain was an unwelcome turn of events.

The word signals to listeners that bad news or a letdown is coming. A teacher might say, “Unfortunately, we won't have time to finish the movie today.” A coach might announce, “Unfortunately, Saturday's game has been canceled.” In each case, unfortunately prepares people for disappointment while acknowledging that the speaker wishes things were different.

You'll often see unfortunately at the beginning of sentences, acting as a signpost for unwelcome information. It's more formal than saying “too bad” or “sadly,” which makes it useful in polite writing and speech. When a scientist writes “Unfortunately, our experiment failed to produce results,” they're professionally expressing disappointment.

Something unfortunate is unlucky or regrettable. Adding -ly turns it into an adverb that describes the speaker's attitude toward a situation: with regret, disappointment, or sympathy for bad luck.