[f. LIGHT sb.] A vessel bearing a light, esp. one with a warning light or lights moored where a lighthouse cannot conveniently be placed; a floating light.
1837. Ht. Martineau, Soc. Amer., II. 11. The office of the light-ship is to tow vessels in the dark through the strait.
1870. Daily News, 2 Sept., 3/6. The visitors to Ramsgate at the present time have had an opportunity afforded them of seeing the far-famed Goodwin lightship at close quarters.