Old English fenol, finul, finol "fennel," perhaps via (or influenced by) Old French fenoil (13c.) or directly from Vulgar Latin *fenuculum, from Latin feniculum/faeniculum, diminutive of fenum/faenum "hay," probably literally "produce" (see fecund). Apparently so called from the hay-like appearance of its feathery green leaves and its sweet odor.
c. 1300, "belonging to all, owned or used jointly, general, of a public nature or character," 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." This is from a reconstructed PIE compound *ko-moin-i- "held in common," compound adjective formed from *ko- "together" + *moi-n-, suffixed form of root *mei- (1) "to change, go, move," hence literally "shared by all."
The 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 German gemein, Old English gemne "common, public, general, universal;" see mean (adj.)), which came to French via Frankish.
Used disparagingly of women and criminals since c. 1300. Meaning "pertaining equally to or proceeding equally from two or more" is from c. 1400. Meaning "usual, not exceptional, of frequent occurrence" is from late 14c. Sense of "not distinguished, belonging to the general mass" is from c. 1400; of things, "ordinary, not excellent," late 14c.
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 that done in public in unity with other worshipers; contrasted with private prayer. Common stock is attested from 1888. Common speech (late 14c.) is the vernacular, as opposed to Latin. Common good (late 14c.) translates Latin bonum publicum "the common weal." The college common room (1660s) is one to which all members have common access.
c. 1300, "a fellowship or brotherhood; early 14c., "people of a community or town, freemen, citizenry;" late 15c., "land held in common," from Old French commune and Medieval Latin communia, and partly from common (adj.). Also compare commons. Latin communis "common, general" (adj.) also served as a noun meaning "common property; state, commonwealth."
1839, from common sense, with ending as in nonsensical, etc. Common-sensible is attested from 1848.
"fennel-like umbelliferous plant of the carrot family found wild in Egypt and Syria and cultivated for its fruit," Old English cymen, from Latin cuminum, from Greek kyminon, cognate with Hebrew kammon, Arabic kammun. Related: Cumic.
"porch at the west end of early churches," the end furthest from the sanctuary (used by penitents not admitted to the body of the church), 1670s, from Late Greek narthex, in classical Greek "giant fennel," a word of unknown origin, perhaps Pre-Greek. The architectural feature allegedly was so called from the fancied resemblance of the porch to a hollow stem. The word also was used in Greek to mean "a small case for unguents, etc." According to Hesiod ("Theogeny"), Prometheus conveyed fire from Heaven to Earth in hollow fennel stalks. Related: Narthecal.
"long, narrow ulcer," late 14c., from Latin fistula "a pipe; ulcer," which is of uncertain origin. Related: Fistular; fistulous (Latin fistulosus "full of holes; tubular").
No certain etymology. The best comparison seems to be with festuca "stalk, straw" and maybe ferula "giant fennel" (if from *fesula): the forms of a "pipe" and a "stalk" are similar. The vacillation between fest- and fist- occurs within festuca itself, and might be dialectal, or allophonic within Latin. [de Vaan]