late 14c., "having the nature of one of the four elements," from Latin elementarius "belonging to the elements or rudiments," from elementum (see element). Meaning "rudimentary, involving first principles" is from 1540s; meaning "simple" is from 1620s. In elementary school (1841) it has the "rudimentary" sense.
metallic element, 1845, named by German scientist Heinrich Rose, who discovered it in 1844 in the mineral tantalite (the source of the element and name tantalum) and columbite. The element was so called because in Greek mythology Niobe was the daughter of Tantalus. With metallic element ending -ium. Related: Niobic.