I moved a small cherry tree a couple of days ago. Will it definitely die?

Nothing is a foregone conclusion in the gardening world but you will certainly have set the cherry tree back. Keep its roots well watered and it might, just might survive. You can expect it to lose most of its leaves, certainly not flower and be a very unhappy tree... Personally I would not lift and move a tree in leaf at this time of year no matter if I had decided it was in the wrong place, guess it all depends what is important to you in an garden.

always while there doorment.you could also cut the top back a lot so more of its energy can go to its roots.as long as a plant is still holding on or you can see the remotest bit of green there is a chance.i had a verigated yucka quite litteraly die down to a dead looking stump.after about a few months it though up 4 hole new plants round it.ive sean a cordaline the same.a friend gave me a biggish normal yucka that had grown at the base of his origional plant.he just snapped it of with a tiny bit of root.hes very clever and grows bonzi trees and i didnt like to sound rude but i thaught this wont grow but ill humer him.this was summer to.i swear its healthy and growing well.everything wants to live and will try its hardest but to a cherry tree youve bean very brutal so like moon sais keep ya fingers crossed.

Thanks for these answers. The cherry survived the move but almost succumbed to windscorch after a storm about ten days ago. 2 or 3 small lateral lower branches are definitely OK, though, so the tree is alive. Not sure what to do now so I've asked another question about that today.

cut out the dead wood is good

Yup cut out all the dead wood, feed and leave alone... and don't even think about moving for several years - if ever!