As a Noun:
1. A period of minutes or hours during which you are waiting for something to happen. To you it seems like a very long period of time.
As a Verb or Adjective:
1. For something to take many minutes or hours to happen, and for you it seems like a long time because you are waiting for it to end, waiting for something to happen, or because it is boring.
1. Used alone to show your impatience, irritation or boredom with something which seems to be taking a long time to happen, to start to happen, or to finish.