The compound term "Sunday school" is a transparent combination of two ancient words. "Sunday," the Old English name for the first day of the week, honors the sun, a concept traceable to Proto-Indo-European sóh₂wl̥. "School" originates from the Greek skholḗ, which intriguingly first meant "leisure, free time," the context in which philosophical discussion and learning occurred. The modern institution emerged in the 1780s in England, founded by Robert Raikes to provide basic literacy and religious education to working children on their one free day, logically applying the "school" concept specifically to the "Sunday" setting. Thus, the term's literal meaning perfectly captures its function as a school held on Sunday.

Structure: sunday (day of the week) + school (educational institution) - sunday: From Old English Sunnandæg, meaning "day of the sun," a calque of Latin dies Solis. Functions as a modifier specifying the day. - school: From Old English scōl, via Latin schola from Greek skholḗ meaning "leisure, lecture place." Functions as the core noun denoting an institution for instruction.