ˈcrack-ˌwillow [f. crack v. + willow.] A name for Salix fragilis, a species of willow with brittle branches. 1670Ray Catal. Plant. 271 The Crack-willow.1806T. Harwood Lichfield 453 Near Stow-pool, the salix fragilis, crack-willow, flourishes.1861Miss Pratt Flower Pl. V. 80.