Calculus: A stone, as in the urinary tract, or calcium salt deposits on the teeth. In Latin, the word calculus means 'a pebble.' Pebbles were once used for counting, from which came the mathematical field of calculus. From Healthy Resources 10 Rheumatoid Arthritis SymptomsWhat Is Exocrine Pancreatic Insufficiency?Understanding COVID-19 Testing and Treatment Featured Centers What Are the Best PsA Treatments for You?Understanding Biologics 10 Things People With Depression Wish You Knew Health Solutions From Our Sponsors Shot-Free MS Treatment Your Child and COVID-19