I-Substance [sub'-stuns] yinto eyenziwe ngenye into ebonakala ngamehlo, okanye yi-matter, yento ethile ekwenziwe ngayo loo nto yenziweyo. Ii-Substances zizinto eziphatheka ngesandla nezibonakala ngamehlo, okanye kusenokwenziwa umlinganiselo wazo. Zenziwe ngamalungu ee-elements amabini nangaphezulu. I-Iron, i-aluminium, amanzi kunye nomoya yimizekelo yee-substances.