class (n.)
c. 1600, "group of students," in U.S. especially "number of pupils in a school or college of the same grade," 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." In early use in English also in Latin form classis.
Meaning "an order or rank of persons, a number of persons having certain characteristics in common" is from 1660s. 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 "group of related plants or animals" is from 1753. Meaning "high quality" is from 1874. Meaning "a division of society according to status" (with upper, lower, etc.) is from 1763. Class-consciousness (1903) is from German Klassenbewusst.
class (v.)
1705, "to divide into classes, place in ranks or divisions," from class (n.) or French classer. Sense of "to place into a class" is from 1776. Related: Classed; classing.
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grace (n.)
late 12c., "God's unmerited favor, love, or help," from Old French grace "pardon, divine grace, mercy; favor, thanks; elegance, virtue" (12c., Modern French grâce), from Latin gratia "favor, esteem, regard; pleasing quality, good will, gratitude" (source of Italian grazia, Spanish gracia; in Church use translating Greek kharisma), from gratus "pleasing, agreeable," from PIE gwreto-, suffixed form of root gwere- (2) "to favor."
Sense of "virtue" is early 14c., that of "beauty of form or movement, pleasing quality" is mid-14c. In classical sense, "one of the three sister goddesses (Latin Gratiæ, Greek Kharites), bestowers of beauty and charm," it is first recorded in English 1579 in Spenser. In music, "an embellishment not essential to the melody or harmony," 1650s. As the name of the short prayer that is said before or after a meal (early 13c.; until 16c. usually graces) it has a sense of "gratitude." As a title of honor, c. 1500.
grace (v.)
c. 1200, "to thank," from Old French graciier "thank, give thanks to; praise," from grace "mercy, favor, thanks, virtue" (see grace (n.)). Meaning "to show favor" (mid-15c.) led to that of "to lend or add grace to something" (1580s, as in grace us with your presence), which is the root of the musical sense in grace notes (1650s). Related: Graced; gracing.