cheeryoudaoicibaDictYouDict[cheer 词源字典]
cheer: [13] Originally, cheer meant ‘face’. It came via Anglo-Norman chere ‘face’ and late Latin cara ‘face’ from Greek kárā ‘head’. As often happens, ‘face’ was taken as a metaphor of the mental condition causing the expression on it, so ‘be of good cheer’ came to mean ‘be in a good mood’; and gradually cheer grew to be used on its own for ‘happy frame of mind, cheerfulness’. It first appears in the sense ‘shout of applause or encouragement’ at the start of the 18th century, when Daniel Defoe identifies it as a nautical usage.
[cheer etymology, cheer origin, 英语词源]
moralyoudaoicibaDictYouDict
moral: [14] Latin mōs ‘custom’ is the starting point of the English family of ‘morality’-words (and its plural mōres was acquired by English as mores in the 20th century). Its derived adjective mōrālis was coined, according to some by Cicero, as a direct translation of Greek ēthikós ‘ethical’, to denote the ‘typical or proper behaviour of human beings in society’, and was borrowed directly into English in the 14th century. Morale [18] was borrowed from French, where it is the feminine form of the adjective moral.

At first it was used in English for ‘morality, moral principles’; its modern sense ‘condition with regard to optimism, cheerfulness, etc’ is not recorded until the early 19th century.

=> morale, mores
cheerful (adj.)youdaoicibaDictYouDict
c. 1400, "full of cheer," from cheer (n.) + -ful. Meaning "elevating the spirits" is from mid-15c. Related: Cheerfully; cheerfulness.
gaiety (n.)youdaoicibaDictYouDict
"cheerfulness, mirth," 1630s, from French gaieté (Old French gaiete, 12c.), from gai "gay" (see gay). In the 1890s, in Britain, especially with reference to a London theater of that name, and the kind of musical shows and dancing girls it presented.
geniality (n.)youdaoicibaDictYouDict
c. 1600, "festivity;" 1831, "cheerfulness," from Late Latin genialitas "festivity, pleasantness," from Latin genialis "pleasant, festive" (see genial).
hilarity (n.)youdaoicibaDictYouDict
mid-15c., from Latin hilaritatem (nominative hilaritas) "cheerfulness, gaiety, merriment," from hilaris "cheerful, gay," from Greek hilaros "cheerful, gay, merry, joyous," related to hilaos "graceful, kindly." In ancient Rome, Hilaria (neuter plural of hilaris) were a class of holidays, times of pomp and rejoicing; there were public ones in honor of Cybele at the spring equinoxes as well as private ones on the day of a marriage or a son's birth.
jollity (n.)youdaoicibaDictYouDict
c. 1300, jolyfte, iolite, from Old French jolivete "gaity, cheerfulness; amorous passion; life of pleasure," from jolif (see jolly).