- al•ka•li[[t]ˈæl kəˌlaɪ[/t]] n. pl. -lis, -lies, adj.1) chem.a) any of various bases, the hydroxides of the alkali metals and of ammonium, that neutralize acids to form salts and turn red litmus paper blueb) any of various other active bases, as calcium hydroxide2) agr. a soluble mineral salt or a mixture of soluble salts, present in some soils, esp. in arid regions, and detrimental to the growing of most crops3) chem. alkaline•Etymology: 1300–50; < MF alcali < dial. Ar al-qalī, saltwort ashes
From formal English to slang. 2014.