From gig + lamp.
gig-lamp (plural gig-lamps)
- (now rare or historical) Either of the lamps on either side of a gig carriage; a headlamp.
1985, Lawrence Durrell, Quinx (Avignon Quintet), Faber & Faber, published 2004, page 1257:But once on the more secure purchase of the macadamised main road, their driver turned off his gig-lamps and let the passengers swell slowly into drowsy sleep as he set sail for distant Avignon.
- (in the plural, dated, slang) Spectacles.
- John Camden Hotten (1873) The Slang Dictionary