a vessel used for purposes of observation.

(a) A vessel of war appointed to protect a harbour and to superintend its marine affairs, and to receive seamen until they are able to join their…

a ship assigned to a particular station (sense 2c), acting as a patrol vessel, or providing troops, refuelling or repair facilities, etc., as…

(a) A boat appointed to row the rounds among the ships of war in a harbour, to observe that their officers keep a good look-out. (b) A boat…

A type of war-vessel adapted for the purposes of reconnoitring. Cf. scout-ship n., scout vessel n. at compounds 1; also scout, n.3 b, which may…

A boat or ship used for reconnoitring, esp. in advance of a fleet.

attributive, designating a boat or ship used for reconnoitring, as lookout boat, lookout ship, etc. Cf. sense 2b.

a boat on patrol duty.

a boat designed to patrol an area; now esp. a small naval vessel used for coastal defence or reconnaissance; = P boat n. at P, n. compounds.

= spy-boat n.

a vessel used for reconnoitring, or scouting in advance of the fleet, or on a river in military operations.

= picket boat n.

a small vessel used for scouting purposes in naval warfare; hence more widely, any motor launch. Also elliptical.

= picket boat n.

A coast-defence ship.

a patrol boat.

Military. A person who watches for and identifies a specified object, esp. enemy aircraft. Also: an aircraft, vessel, etc., used for this purpose…

a picket boat or aircraft equipped with radar for the detection of enemy vessels; frequently attributive.