General English

General Science

  • verb to cover something with an insulating material to protect against cold or to stop heat escaping


  • noun a delay, especially the time interval between an input and the resultant output


  • noun the time taken for an image to be no longer visible after it has been displayed on a CRT screen


  • Time that an activity follows, or is delayed from the start or finish of its predecessor(s). Sometimes called an offset.


  • The time interval that elapses between events which are considered together. Also, any such difference in phase, such as that between waves. For instance, a lag angle.
  • The state or condition of lag (1) occurring. Also, that which lags. For example, a lagging current.
  • To fall behind in general. Also, to stay behind.
  • The time interval that elapses between the transmission of a signal and its reception.
  • The time interval that elapses between a given action and its intended effect. For instance, the difference between a corrective action, and the change in the desired output.
  • In a camera tube, the persistence of the electric image after a scene change.

Information & Library Science

  • verb to make slower progress than other people
  • verb to slow down so that less is produced


  • verb to inform (on someone), to tell tales. A prisoners’ and schoolchildren’s word, this was British slang of the 19th century with the meaning of ‘betray to the authorities’. It has survived in Australia but has not been heard in the UK since the turn of the 20th century. Its frequent use in Australian TV soap operas during the 1990s may result in the reintroduction of the term.

Origin & History of “lag”

English has three distinct words lag. The verb ‘fall behind’ (16th c.) is perhaps of Scandinavian origin (Norwegian has lagga ‘go slowly’), although a link has been suggested with the lag of fog, seg, lag, a dialect expression used in children’s games which represents an alteration of first, second, last. Lag ‘insulate’ (19th c.) comes from an earlier noun lag ‘barrel stave’, which was also probably borrowed from a Scandinavian language (Swedish has lagg ‘stave’); the original material used for ‘lagging’ was wooden laths. And finally the noun lag ‘prisoner’ (19th c.) seems to have come from an earlier verb lag, which originally meant ‘steal’, and then ‘catch, imprison’; but no one knows where this came from.