MIcrosoft Outlook stopped working on Yosemite
After to Alistair's comment, I did some more general googling. I found some suggestions that the best solution was to rebuild the identity, so that's what I did:


go to ~/Documents/Microsoft User Data
make a "backup folder"
drag the contents of ~/Documents/Microsoft User Data/Office 2011
Identities into the backup folder
relaunch Outlook and configure
as if it's a fresh install.


This has things working again.