<p><strong>Noun</strong></p><ul><li>Also called cinder.</li><li>The more or less completely fused and vitrified matter separated during the reduction of a metal from its ore.</li><li>The scoria from a volcano.</li><li>Waste left over after the re-sorting of coal.</li></ul><p><strong>Verb</strong></p><ul><li>(used with object)<ul><li>Slagged, slagging: to convert into slag.</li><li>Metallurgy: to remove slag from (a steel bath).</li></ul></li><li>(used without object)<ul><li>Slagged, slagging: to form slag; become a slaglike mass.</li></ul></li></ul>