noun-modifying (irregular)
Prenominal adjective used in formal or educational contexts to describe the first stage of something, especially education.
Elementary education is the foundation for all children.
I reviewed the differentiation of elementary functions.
初等 (same pronunciation) means 'elementary' as in 初等教育 (elementary education), while 初頭 refers to the early part of a time period like a century or era.
Compound of 初 (first, beginning) and 等 (class, grade). The exact historical derivation is uncertain, but the spelling is conventionally associated with 'elementary' or 'primary' level.