actinPronunciation: /ˈaktɪn/Definition of actin noun [mass noun] Biochemistry a protein which forms (together with myosin) the contractile filaments of muscle cells, and is also involved in motion in other types of cell. Origin: 1940: from Greek aktis, aktin- 'ray' + -in1actin in other Oxford dictionaries Definition of actin in the US English dictionary
