An older typesetting practice where a compositor, running out of a specific letter in the typecase, inserts a piece of type of identical width upside down. This leaves a solid black rectangle or feet marks on the galley proof, signaling the proofreader and compositor exactly where the correct character must be swapped in once the distributed type is replenished.
Heard on the job
I'm completely out of lowercase e's, so I'll have to turn a few letters until we distribute that dead form.
Insider tip
A turned letter was intentionally highly visible on a proof sheet so it would never accidentally make it to the final press run.
Also heard as
- turned letter