late 14c., "having the nature of one of the four elements," from Middle French elementaire and directly 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.[elementary etymology, elementary origin, 英语词源]