A printing term which describes wet ink coming in contact with paper and spreading as it is transfers. As the halftone dots are applied to the paper, the wet ink spreads, causing the dots to increase in size and halftones to appear darker. Paper weight, type of paper (coated or uncoated) and press type (especially web presses) affect the amount of dot gain in a given printed piece.
You may compensate for dot gain by calculating the dot gain before a print job and lessen the density of the images to be printed before you output film. See also dot compensation, four-color process, and halftone.