mark something ↔ up phrasal verb ( see also ↑ mark )
1 . to increase the price of something, so that you sell it for more than you paid for it OPP mark down :
Compact discs may be marked up as much as 80%.
⇨ ↑ mark-up
2 . to write notes or instructions for changes on a piece of writing, music etc:
I have to mark up the pages and send them back to the printer.