I am assuming you mean the following schools of magic ...
* Abjuration
* Conjuration
* Divination
* Enchantment
* Evocation
* Illusion
* Necromancy
* Transmutation
It goes a bit further back than old D&D, the schools of magic (and the descriptors) actually correspond to "real world" magic.
Abjuration is derived from old Latin abjurare meaning "to swear away" or "do away" which is what Abjuration is about ... protection ... doing away with harm.
Conjuration was usually associated with summoning devils and demons, however it was originally to do with making promises (which is essentially what a conjurer does when summoning things).
Divination was the old art of prediction which existed (and still does) throughout cultures in history. The watching for signs, the cutting up of animals and reading entrails, etc.
Enchantment was originally the placing of a spell on person or object. It was derivied from Latin incantare which meant putting a spell on someone. It was mainly to do with affecting one person at a time. Normally it was designated as coercion magic.
Evocation was originally synonomous with Conjuration - the bringing forth of spirits to do your bidding. However it evolved to be synonomous with Invocation - the calling forth of spirits into the body. In either state, the evoke spirits would inhabit objects or people or animals and the effects produced (fire/smoke/etc) were by the power of the spirit.
Illusion, the creationion of illusions for entertainment is as old as history. We marvel at stage magicians even now. They are illusionists and this this school represents them.
Necromancy was the art of Divination by using the spirits of the dead. Originally an Ancient Greek word it was derived from Divination with the Dead (or something like that).
Transmutaion is a turning one thing into another. Alchemy throughout the ages attempted to make Lead into Gold using Transmutation principles. They were always searching for the Philosopher's stone.
Hope that is what you were after.
D