calmodulinPronunciation: /kalˈmɒdjʊlɪn/Definition of calmodulin noun [mass noun] Biochemistry a protein which 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 US English dictionary