reticulinPronunciation: /rɪˈtɪkjʊlɪn/Definition of reticulin noun [mass noun] Biochemistry a structural protein resembling collagen, present in connective tissue as a network of fine fibres, especially around muscle and nerve fibres. Origin: late 19th century: from reticular (see reticulum) + -in1reticulin in other Oxford dictionaries Definition of reticulin in the US English dictionary