JSmem 14:206 :ܛ݁ܝܫܝܢ ܒܬܕܐ ܕܢܒܥܐ ܠܚ݂ܡܐ‏ : they smear (bitterness) on the breast so that (the child) wants bread
See the entire entry for ṭwš vb. to smear