Why is the ninth month called September?
late 14c., from Late Latin cyclus, from Greek kyklos "circle, wheel, any circular body, circular motion, cycle of events," from PIE *kwel- "to roll, to move around, wheel" (cf. Sanskrit cakram "circle, wheel," carati "he moves, wanders;" Avestan caraiti "applies himself," c'axra "chariot, wagon;" Greek polos "a round axis" (PIE *kw- becomes Greek p- before some vowels), polein "move around;" Latin colere "to frequent, dwell in, to cultivate, move around," cultus "tended, cultivated," hence also "polished," colonus "husbandman, tenant farmer, settler, colonist;" Lithuanian kelias "a road, a way;" Old Norse hvel, Old English hweol "wheel;" Old Russian kolo, Polish koło, Russian koleso "a wheel").
1842, "revolve in cycles," from cycle (n.). Meaning "to ride a bicycle" is from 1883. Related: Cycled; cycling.
cycle cy·cle (sī'kəl)
An interval of time during which a characteristic, often regularly repeated event or sequence of events occurs.
A single complete execution of a periodically repeated phenomenon.
A periodically repeated sequence of events.