<p><strong>Noun</strong></p><ul><li>plural alkalis, alka­lies.</li><li>Chemistry: any of various bases, the hydroxides of the alkali metals and of ammonium, that neutralize acids to form salts and turn red litmus paper blue.</li><li>any of various other more or less active bases, as calcium hydroxide.</li><li>(not in technical use) an alkali metal.</li><li>Obsolete: any of various other compounds, as the carbonates of sodium and potassium.</li><li>Agriculture: a soluble mineral salt or a mixture of soluble salts, present in some soils, especially in arid regions, and detrimental to the growing of most crops.</li></ul><p><strong>Adjective</strong></p><ul><li>Chemistry: alkaline.</li></ul><p><strong>End of Response</strong></p>