This evolution in language is what etymology is all about. Etymology is the study of or branch of linguistics dealing with word origin and development. Where a word was created or formed and it's Development through history. Words evolve, that's a given. Proof of this can be found in the twenty-volume Oxford English Dictionary (O.E.D.), which is known by scholars as the definitive resource for word origin and definition. A word that had definition 1 in 1492 will still hold that meaning; but it will also evolve into a new version or use of that meaning, creating definition 2. Both meanings are correct and the application of the definition of the word will depend on it's usage in conversation or context.
When it comes to using a word as a label, we have to think about how the word was used when it originated and not just how it's perceived today. Warlock is a good example of this. It's origination was to define a liar, a traitor or "an oath breaker". But today many non-pagans use it as the title for a male witch. Which most witches don't care for.
So let's first define a common Understanding of some of the labels used in the pagan community.
Old Latin (OL)
Low Latin (LL)
Latin (L)
Old English (OE)
Middle English (ME)
Modern English (E)
Classical Greek (CG)
The latin language used before 75 BC
Nonclassical Latin, esp. in the medieval period 600 - 1500 AD
Modern Latin, used since 1500 AD
Anglo-Saxon English used primarily between 400 - 1100 AD
English language used between 1100 - 1500 AD
English language used since the 1500 AD
Greek language used between 700 - 300 BC
Wicca
From LL - the Saxon wicca/wicce
1. Old English: An old Saxon noun with a masculine ending, pronounced "witch'-ah" (not "wick'-ah"). 1a. The feminine form "wicce", pronounced "witch'-eh".
2. Modern English: A modern label for the pagan tradition of Wicca, established by Gerald Gardner.
Witchcraft
From OE wiccecraeft, ME wicchecrafte
1. Old English: the power or practices of witches; black magik. The craft of the wise.
2. Middle English: A neopagan religious practice that strives to live in balance with nature and natural forces.
Pagan
From LL paganus, L pagus
1. A person who is not a Christian, Muslim, or Jew; (Any Abrahamic origin belief system)
2. Heathen: formerly, sometimes applied specifically. to a non-Christian by Christians
Neopagan
From CG neos, L paganus
1. Any group of pagan religions that define their beliefs as nature based.
From the old world, using wicca/wicce and witch interchangeably is incorrect. In our society today; the creation of Gerald Gardner's Wiccan tradition clouds the use of these words. In common conversation, when someone mentions Wicca they're rarely referring to witch; and more often referring to the traditional practice of Gerald Gardner.
In the old world, Witchcraft was a practice, more often known as the craft of magik. The word was used in this context during 1100-1200 AD. Today it is a label used to define a religious practice specific to a set of neo-pagan beliefs. This is not a new concept; it actually started during the 13th century and is thanks to the early Christian Church. But we'll get into that later on.
Over time, the category of traditions (or denominations) under Witchcraft has slowly returned to their own roots. In part due to the neopagan revivals and increased acceptance. In addition, there has become a clarifying divide between other pagan religions and Witchcraft. For instance, Satanism isn't considered to be part of Witchcraft. They stand on their own as a pagan religion, merely because they do not follow the doctrine set forth by Abrahamic religions. But this can also be said for Hindu, Buddhist and other non-Abrahamic religions. By definition they too fall into the category of pagan religions. Society however does not think of these other religions as pagan.
Free eBooks (Can Be Downloaded):
George Lyman Kittredge - Notes On WitchcraftWalter Rowe - Mysterious Delusions Witchcraft In Salem
Reginald Scot - The Discoverie Of Witchcraft
Michael Harrison - The Roots Of Witchcraft