Calla is a Greek word meaning 'beauty'. As far as the meaning of the word goes, 'beauty' really fits this beautiful purple flower. I learned that Calla lilies are native to South Africa and Malawi.
The first person to catalog the calla in the 18th century was a Swedish botanist in the 18th century. But it isn't really a calla lily. Rather it is in the same family as the philodendron. A German botanist tried to correct the mistake. But the name remained. It may not be accurate but the definition of the word fits anyway.