calmodulin Syllabification: (cal·mod·u·lin)Pronunciation: /kalˈmäjələn/Definition of calmodulin noun Biochemistry a protein that binds calcium and is involved in regulating a variety of activities in cells. Origin: 1970s: from cal(cium) + modul(ate) + -in1calmodulin in other Oxford dictionaries Definition of calmodulin in the British & World English dictionary