WordNet (r) 3.0 (2006):

sidelight
    n 1: light carried by a boat that indicates the boat's
         direction; vessels at night carry a red light on the port
         bow and a green light on the starboard bow [syn:
         sidelight, running light]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "sidelight":
   account, acquaintance, announcement, blue book, briefing, bulletin,
   communication, communique, data, datum, directory, dispatch,
   emanation, enlightenment, evidence, facts, factual information,
   familiarization, gen, general information, guidebook, handout,
   hard information, highlight, illumination, incidental information,
   info, information, instruction, intelligence, irradiance,
   irradiancy, irradiation, knowledge, light, light source,
   luminous energy, mention, message, notice, notification,
   photosensitivity, presentation, promotional material, proof,
   publication, publicity, radiance, radiancy, radiant energy,
   radiation, release, report, statement, the dope, the goods,
   the know, the scoop, transmission, visible radiation, white book,
   white paper, word