di·ges·tion 
/dəˈjesCH(ə)n,dīˈjesCH(ə)n/ 
noun 
the process of breaking down food by mechanical and enzymatic action in the alimentary canal into substances that can be used by the body. 
synonyms: breaking down, maceration, dissolution; More 
a person's capacity to break down food into substances that can be used by the body. 
plural noun: digestions 
"bouts of dysentery impaired his digestion" 
CHEMISTRY 
the process of treating a substance by means of heat, enzymes, or a solvent to promote decomposition or extract essential components.