Atherosclerosis comes from the Greek words athero (meaning gruel or paste) and sclerosis (hardness).

Atherosclerosis is the process in which deposits of fatty substances, cholesterol, cellular waste products, calcium and other substances build up in the inner lining of an artery and form a plaque.

References

http://www.nhlbi.nih.gov/health/dci/Diseases/Atherosclerosis/Atherosclerosis_WhatIs.html