any of the oxides of barium, radium, strontium, calcium, and, sometimes, magnesium.
Origin
1810-20
British Dictionary definitions for alkaline earth
alkaline earth
noun
1.
Also called alkaline earth metal, alkaline earth element. any of the divalent electropositive metals beryllium, magnesium, calcium, strontium, barium, and radium, belonging to group 2A of the periodic table
2.
an oxide of one of the alkaline earth metals
alkaline earth in Medicine
alkaline earthn. The oxides of calcium, strontium, radium, and barium, and sometimes magnesium.