Entry 1 sense Webster, 1913 Crow-silk /(kr?"s?lk`)/ · Crow·-silk · IPA 01 n. A filamentous fresh-water alga (Conferva rivularis of Linnaeus, Rhizoclonium rivulare of Kutzing). 1. A filamentous fresh-water alga (Conferva rivularis of Linnaeus, Rhizoclonium rivulare of Kutzing).(Bot.)