1) Low-pressure impactor 2) Pelican State inst 
(Digital cameras and photo printers) Lines per inch. Unit of measurement for the resolution of printed images. (Dots per inch)
Low-Probability-of-Intercept
LG&E Power Inc.
Liner Per Inch. A measure of resolution, usually screen frequency in halftone
Lines Per Inch
Low Probability of InterceptLines per inch - refers to the quality of a halftone screen. it is important to distinguish it from dpi which refers to the resolution of a device or image. commonly lpi is used at exactly half of the dpi of the device or image, i.e. 300dpi would equal 150lpi.
(Lines-per-inch) This actually refers to the number of dots-per-inch in a halftone but the term is LPI and NOT DPI. You can see where LPI and DPI can get confused. This term is also known as the frequency in computer graphics (frequency of lines-per-inch). The standard LPI of a screen printable design is 35 lpi to 45 lpi for cartoon type work and f...
Lines Per Inch. A measure of resolution, usually screen frequency in halftone. 
Linux Professional Institute
Lunar and Planetary Institute
acronym: low-pressure impactor
(Lines per Inch) The number of lines per inch in a halftone screen. As a general rule, the higher the lpi, the higher the printed resolution and quality.