So I just hit 5th level on my wizard, which means Spontaneous Divination goodness.
The only problem is, while there are an extremely large number of feats, ACFs, general rules, etc. that refer to spells a wizard "knows," there seems to be no definition for what spells those are.
I asked a while back in the RAW Q&A thread and received the following answer
A Wizard may know any number of spells, but the number known is a limited subset of their class list. Spells known refers to those spells the Wizard has learned either automatically from class abilities (initial level 0 and 1 spells, plus 2 spells per subsequent level) or as demonstrated by the relevant successful Spellcraft checks and study days. See the primary definition of learn: "to acquire knowledge of or skill in by study, instruction, or experience". It is not necessary for the Wizard to have written these spells in a spellbook, but they must have succeeded on all tasks leading up to the actual writing.
That seems to be based more on a reading of the dictionary than of the Player's Handbook though, because I can't find anything in the latter to directly confirm it.
I did, however, find the following in the PHB glossary:
Originally Posted by Player's Handbook I, pg. 310
known spell: A spell that an arcane spellcaster has learned and can prepare. For wizards, knowing a spell means having it in their spellbooks. For sorcerers and bards, knowing a spell means having selected it when acquiring new spells as a benefit of level advancement.
Relevant sentence bolded in red. Normally I'd say that answers my question, but
1. I don't know whether the glossary is considered to be full/legitimate rules text, seeing as it's not reflected anywhere in the SRD that I can find.
2. It's unclear or counterintuitive in some cases. For instance, if a wizard loses their spellbook, do they still "know" the spells that were in it (though either way they can't prepare them without the book)?