classyoudaoicibaDictYouDict[class 词源字典]
class: [16] Latin classis originally denoted ‘the people of Rome under arms, the ancient Roman army’; it appears to come from an earlier unrecorded *qladtis, a derivative of the base *qel- ‘call’, which points to an underlying sense ‘call to arms’. Under the terms of the constitution attributed to Servius Tullius, a 6thcentury BC king of Rome, the army, and hence the people, was divided into six such classes, membership of each based originally on the amount of land held, and latterly on wealth in money terms.

English first adopted the word in this antiquarian sense (which provided the basis for the modern application to social class), but its widespread use in the language probably began in the sense ‘group of pupils’. The derivatives classic [17] and classical [16] come from Latin classicus, probably via French classique; in Latin, the adjective signified ‘of the highest class of Roman citizen’, whence the word’s presentday approbatory connotations.

[class etymology, class origin, 英语词源]
class (n.)youdaoicibaDictYouDict
c. 1600, "group of students," from French classe (14c.), from Latin classis "a class, a division; army, fleet," especially "any one of the six orders into which Servius Tullius divided the Roman people for the purpose of taxation;" traditionally originally "the people of Rome under arms" (a sense attested in English from 1650s), and thus akin to calare "to call (to arms)," from PIE root *kele- (2) "to shout" (see claim (v.)). In early use in English also in Latin form classis.

School and university sense of "course, lecture" (1650s) is from the notion of a form or lecture reserved to scholars who had attained a certain level. Natural history sense is from 1753. Meaning "a division of society according to status" (upper, lower, etc.) is from 1772. Meaning "high quality" is from 1847. Class-consciousness (1903) is from German klassenbewusst.
class (v.)youdaoicibaDictYouDict
1705, "to divide into classes," from class (n.) or French classer. Sense of "to place into a class" is from 1776. Related: Classed; classing.