Glossary of Printing Terms:
LPI

Lines per inch

1. A measurement of the number of lines of type in an inch, determined by measuring from baseline to baseline. Example: 6 LPI indicates that 6 lines of type would fit in one inch.

2. The number of lines of dots per inch in a halftone screen or linescreen. A screen with a higher lpi, such as 200 lpi has many smaller dots which provide finer detail and a sharper image clarity. The LPI of a halftone screen is also called frequency.