commonyoudaoicibaDictYouDict[common 词源字典]
common: [13] Common comes ultimately from an Indo-European base *moi-, *mei-, signifying ‘change, exchange’, which also produced English immune, mutate, mutual, and remunerate. A derivative of this base, *moin-, *mein- seems to have joined up with the Indo- European collective *kom- to produce *komoin-, *komein- ‘shared by all’.

In Germanic this became *gamainiz, source of English mean ‘despicable’, while in Latin it gave commūnis, source, via Old French comun, of English common. Both the Latin and French forms have given English a number of derivatives: from the former we have community [14] (Latin commūnitātis), communion [14] (Latin commūniō), and communicate [16] (Latin commūnicāre), while the latter has yielded commune [13] (Old French comuner) and communism [19] (French communisme, coined around 1840).
=> communicate, communism, community, immune, mean, mutual, mutate, remunerate[common etymology, common origin, 英语词源]
common (adj.)youdaoicibaDictYouDict
c. 1300, "belonging to all, general," from Old French comun "common, general, free, open, public" (9c., Modern French commun), from Latin communis "in common, public, shared by all or many; general, not specific; familiar, not pretentious," from PIE *ko-moin-i- "held in common," compound adjective formed from *ko- "together" + *moi-n-, suffixed form of root *mei- (1) "change, exchange" (see mutable), hence literally "shared by all."

Second element of the compound also is the source of Latin munia "duties, public duties, functions," those related to munia "office." Perhaps reinforced in Old French by the Germanic form of PIE *ko-moin-i- (compare Old English gemæne "common, public, general, universal;" see mean (adj.)), which came to French via Frankish.

Used disparagingly of women and criminals since c. 1300. Common pleas is 13c., from Anglo-French communs plets, hearing civil actions by one subject against another as opposed to pleas of the crown. Common prayer is contrasted with private prayer. Common stock is attested from 1888.
common (n.)youdaoicibaDictYouDict
late 15c., "land held in common," from common (adj.). Commons "the third estate of the English people as represented in Parliament," is from late 14c. Latin communis also served as a noun meaning "common property, state, commonwealth."