What Is The Origin Of The Word Purple?

The word purple has its origin in the word 'purpura' that describes a kind of shellfish from which purple dye was being produced so that clothes could be dyed. The word became popular when it started being used to be given colour to royal attire and thus royalty has also been associeted with it.
      
But nowadays the word is being used to describe a number of things and many of them are phrases and idioms. The term purple patch is  used to describe a period in which somebody is enjoying a spout of success in his life; and when some body  uses the word purple heart he is talking about a medal that is given to the armed forces in the US and it has been given to those who have been wounded while in battle.