Farewell in a dream often signifies a leave-taking, something permanent or definite.
Some people believe that farewell in a dream represents sorrowful feelings of parting. A person may have this type of dream if they are about to take up an extended trip and will be away from their loved ones for the duration of the trip.
Others believe that farewell in a dream can also represent someone you have lost forever or it simply means goodbye. It can also represent an ending and welcoming the new beginning, to wish somebody well on their new journey, even if one does not know them personally.
There are many causes for dreams about saying goodbye. For example, you may be feeling guilty about something that happened, you may be afraid of change or you may know that your relationship has finished but want to hold on until the last moment.