by bad luck
"unfortunately it rained all day"
"alas, I cannot stay"
Happening through bad luck, or because of some unfortunate event.
"Unfortunately, a sudden rainstorm ruined our picnic plans right before we were about to eat."
In plain English: Unfortunately is used to say that something bad has happened when you really hoped it wouldn't.
"Unfortunately, I cannot make it to the party tonight because I am sick."
Usage: Use unfortunately to express regret about an unlucky outcome rather than describing the inherent nature of something as being unfortunate. Place it at the beginning of a sentence to soften bad news or after "I'm" and before the main verb when sharing personal disappointment.
The word unfortunately comes from combining the prefix un- with fortunate and adding the suffix -ly to create its current meaning. It entered English as a straightforward formation that simply negates the idea of being lucky before an event occurs.