Definition: A percentage added to the cost to get the retail selling price.
Also Known As: markon, markup
A widget bought for $5 and sells for $10 has a mark-up of 100%. (Add $5 to the $5 cost to get the price.) A widget bought for $2, which sells for $3, has a mark-up of 50%, (Add $1 to the $2 cost to get the price.)