Is there a key that I can use to stop the Dock from appearing when hidden?

You should not need to re-enter the command.

Set a moderate or large delay (12 seconds shown):

defaults write com.apple.dock autohide-delay -float 12; killall Dock

And then use Command-Option-D to reveal the Dock when and as needed, or hold for the delay to reveal if the mouse or trackpad or keyboard is offline. You can then (effectively) use Command-Option-D as a Dock toggle.

Tom Wolsky wrote:

I'm working in fullscreen and sometimes I'm working on an image and need to go right to the edge of the screen. The Dock is always hidden, but is there anything I can do to prevent it from popping open. Honestly I hardly ever use the Dock except to move things to the Trash. For me the Dock is more an annoyance than a help. I'd love if there was a keychord like ⇧ ⌥ that I could hold with one hand and would let me stop the Dock from appearing when I have to. Is there anything like that at all? I found a way with Terminal

defaults write com.apple.Dock autohide-delay -float 5 && killall Dock

that let's you keep the Dock hidden for a time. That kills the Dock opening, but it's a one time use. I'd have to re-enter the Terminal command every time I used the Dock or touched the screen edge where it is. I don't know how to script it to be a permanent function.

Thanks very much for any help.

Well not perfect however you can try reducing the default tilesize from 16 to 1

 defaults write com.apple.dock tilesize -int 1  && killall Dock