Baseline
From The Glossary of Digital Photography
A term used in typography to indicate the base upon which letters set. Letters that descend below the line, such as j, p, and y, will have a portion below the baseline.

ONLINE GLOSSARY OF DIGITAL PHOTOGRAPY
A term used in typography to indicate the base upon which letters set. Letters that descend below the line, such as j, p, and y, will have a portion below the baseline.