Longman Dictionary of Contemporary English
n. Paper ruled into small squares, usually of equal size, for use in drawing graphs or other charts.
n. paper that has lines to permit drawing graphs
Graph paper, graphing paper, or millimeter paper is writing paper that is printed with fine lines making up a regular grid. The lines are often used as guides for plotting mathematical functions or experimental data and drawing two-dimensional graphs. It is commonly found in mathematics and engineering education settings and in laboratory notebooks. Graph paper is available either as loose leaf paper or bound in notebooks. It is becoming less common as computer software, such as spreadsheets and plotting software, has supplanted many of the former uses of graph paper. Some users of graph paper now print pdf images of the grid pattern as needed rather than buying it pre-printed. There are websites that will generate pdfs of graph paper to the user's specifications.