Why is "will not" contracted as "won't"? [duplicate]

Possible Duplicate:
What is “won't” a contraction of?

The Why is "cannot" spelled as one word? post brought back another oddity I noticed when learning English. The contraction won't seems to break a common pattern in similar contractions:

• cannot => can't
• do not => don't
• should not => shouldn't
• would not => wouldn't

In these examples, the o sound in not is dropped and the letter o (no in the case of cannot) is replaced with an apostrophe.

However, will not => won't drops ill from will and replaces it with the o from not. This contraction is probably derived from shifts in speech rather than writing. How did the contraction won't emerge?

Solution 1:

The building pattern you are proposing is not what happened. As you can see here, will not was built from woll + not, which assimilated to wonnot and then to won't.

The use of woll comes from the Proto-Indo-European stem wel- or wol-, refelcted still in the German verb wollen: to will, desire, wish.