1. an item of incidental information.
  2. either of two lights carried by a vessel under way at night, a red one on the port side and a green on the starboard.
  3. light coming from the side.
  4. a window or other aperture for light in the side of a building, ship, etc.
  5. a window at the side of a door or another window.

Origin of sidelight

First recorded in 1600–10; side1 + light1 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for side-light

Historical Examples of side-light

  • Isabel went into the dark entry, and pressed her face against the side-light.

    Tiverton Tales

    Alice Brown

  • Perhaps the reader may be interested in a side-light on this subject.

  • It is only by a side-light that any connection between the saint and the custom can be traced.

    The Royal Mail

    James Wilson Hyde

  • Emerson has treated this matter partially and from a sort of side-light.

    The English Novel

    Sidney Lanier

  • He is one of the characters that throw a side-light on our lives.

British Dictionary definitions for side-light


  1. light coming from the side
  2. a side window
  3. either of the two navigational running lights used by vessels at night, a red light on the port and a green on the starboard
  4. British either of two small lights on the front of a motor vehicle, used to indicate the presence of the vehicle at night rather than to assist the driver
  5. additional or incidental information
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for side-light



also side-light, c.1600, "light coming from the side," from side (adj.) + light (n.). Figurative meaning "incidental information on a subject" is attested from 1862.

Online Etymology Dictionary, © 2010 Douglas Harper