Cycle (unit)

A cycle was a unit of time used by several species.

Romulan cycle

One Romulan cycle was approximately equivalent to no more than 29.35 Earth minutes. A Romulan officer noted they had no motion on their sensors for twenty cycles. James T. Kirk had also noted in a log that the USS Enterprise had been motionless for 9 hours and 47 minutes. (TOS: "Balance of Terror")

In the background chatter of TNG: "Unification II", it is possible to hear dialog noting something about "two cycles". The exact line is "We are very close now... within two more cycles."

Argrathi cycle

An Argrathi cycle was equivalent to one Earth year. The crime of espionage required a minimum of fifteen cycles of correction on Argratha, and Miles O'Brien served 20 cycles, the equivalent of twenty Earth years (though his entire imprisonment was actually an implanted memory). (DS9: "Hard Time")

Borg

Borg seemed to count time in cycles. For example, assimilated children were put in a maturation chamber for 17 cycles. (VOY: "Mortal Coil")

Seven of Nine spent five years in a maturation chamber, so one cycle could conceivably equate to approximately 107.4 days.

Other uses

• Cycles seemed to have a strong role in the religion of Borothan pilgrims. Amongst their religious concepts were the Cycle of renewal, the Cycle of creation and the idea that the universe went through cycles of rebirth.
• REM cycle
• the life cycle

A cut scene from "The Inner Light" mentions the Ring cycle.

The use of the word cycle as a "generic" alien unit of time is common in science fiction, to the point that it is almost a cliché. No doubt this was a factor to its many uses in the Star Trek universe.