None of my dictionaries, nor this shabdkosh, seem to have alvidaa (as in the film title kabhi alvida na kahna). It’s evident that it’s translated as ‘good bye’, but what is its origin? Is it a relatively new coinage?
Peter, the Oxford Hindi-English by R.S. McGregor contains it. This dictionary is the one to get if you don’t have it.
alvidA is indeed derived from the Arabic al vida’. It’s meaning is 1. the last Friday in RamazAn, 2. goodbye!
In the same dictionary, a visit to the word vidA directs you to bidA, no doubt the Hindi form of it, yet in parenthesis containing Arabic. vidA’, and the meaning given is 1. permission to depart; taking leave. 2. departure, etc.