Cycle has a y where an i would do, and that is the Greek marker: the letter upsilon, transliterated y through Latin. The Greek is kyklos, "circle, wheel, any circular body," and also "circular motion, a cycle of events." Underneath it is an old Indo-European root meaning "to revolve," doubled up on itself — the word is literally a reduplication, a little wheel of a word.
English took it in the late 1300s, first spelled cicle, in a strictly astronomical sense: a period of time after which the same phenomena return in the same order. The generalisations came slowly — any recurring round of events from the 1660s, a single complete period from 1821, a long age from 1842, an engine's oscillations by 1884. The bicycle senses are the youngest of all, cycle standing in for motorcycle from 1870 and for bicycle by 1881.
cycle (n.) late 14c., cicle , "perpetual circulating period of time, on the completion of which certain phenomena return in the same order," especially and originally in reference to astronomical phenomena, from Old French cicle and directly from Late Latin cyclus , from Greek kyklos "circle, wheel, any circular body," also "circular motion, cycle of events," from PIE kw(e)-kwl-o- , a suffixed, reduplicated form of the root *kwel- (1) "to revolve, move round." From 1660s as "any recurring round of operations or events" (as in life cycle ). From 1821 as "single complete period in a cycle." Extended by 1842 to "any long period of years, an age." In literary use, "the aggregate of the legends or traditions around some real or mythical event or character" (1835). By 1884 as "recurring series of oscillations or operations in an engine, etc." From 1870 as short for motorcycle ; by 1881 as short for bicycle or tricycle . also from late 14c. cycle (v.) 1842, "revolve in cycles, occur or recur in cycles," from cycle (n.). Meaning "to ride a bicycle" is by 1881 (implied in cycling ). Related: Cycled . also from 1842
cycle came in through Norman French, and its spelling follows that family's conventions.
What gives it away on the page
| c said as /s/ before e, i, y | The soft-c convention is Romance; Old English had no use for it.city, cell, cycle, pencil |
Norman French in the spelling guide · guess another word's family