Spithead, roadstead, at the entrance of Portsmouth harbour, Hants, extending 2 miles NW. and SE. along the SW. side of the Spit Sand, with an average breadth of 1½ mile; its natural advantages for safe anchorage, and its vicinity to the great naval establishments of Portsmouth, have made it a favourite rendezvous of the British fleet, and the system of fortifications intended for the defence of Portsmouth harbour and dockyards is also designed as a protection for the roadstead at Spithead, a term which is often applied, in a more extended sense, to the whole of the channel which separates the NE. coast of the Isle of Wight from the mainland of Hants.

(John Bartholomew, Gazetteer of the British Isles (1887))