free-runv.
/ˌfriːˈrʌn/, U.S. /ˈfriˈrən/ 1. intransitive. Of a signal generator, timepiece, etc.: to operate independently, without external influence or intervention. Also in extended use: to run freely, loosely, or easily.
ΚΠ
1949 A. W. Keen Princ. Television Reception iv. 119 The generator cannot be allowed to ‘free-run’, even if its frequency can be set precisely to the required value.
1971 J. F. Golding Measuring Oscilloscopes iv. 95 Selection of this mode causes the trigger bistable to free-run at some low frequency—such as 50 Hz—and the trigger level control is rendered inoperative.
1987 Railnews (British Rail) Oct. 38/6 Clocks which could ‘free run’ to maintain accurate time if they became disconnected from the master clock.
1998 N. Earls Bachelor Kisses (1999) iv. 61 Sitting here,..ideas free-running somewhat dangerously.
2001 J. Watkinson Art of Digital Audio (ed. 3) ix. 531 The scanner free-runs at approximately twice normal speed.
2. intransitive. Biology. Of a circadian rhythm: to operate in the absence of, or independently of, light or other external cues indicating the time of day. Also (of an organism): to maintain a circadian rhythm in this way.
ΚΠ
1959 C. S. Pittendrigh & V. G. Bruce in R. B. Withrow Photoperiodism vii. 491 When free running in aperiodic conditions its phase can be shifted by single light signals.
1965 Amer. Jrnl. Nursing 65 No. 5. 79/1 The rhythm now no longer maintains a 24-hour period, but rather ‘free runs’ with a period-length slightly but significantly shorter.
1987 Some Math. Questions in Biol. 19 189 A parametric light regime is one in which a steady light is maintained for a number of days before the animal free-runs in the dark.
1996 New Scientist 3 Feb. 43/1 Synchronising sleep-wake cycles in blind people who, lacking the entraining influence of the light-dark cycle, often ‘free-run’ so that for long periods of time they are going to work in the middle of their own biological night.
2005 J. H. Benington in C. A. Kushida Sleep Deprivation xxiv. vi. 498 Their biological clock ‘free runs’ at its endogenous period.
This is a new entry (OED Third Edition, June 2008; most recently modified version published online March 2022).
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v.1949