(slang, US) a naive or clueless person.

A four-stroke engine. / A vehicle or machine powered by a four-stroke engine.

Of or relating to a design of internal combustion engine in which the pistons perform four strokes per engine cycle: intake, compression, power, exhaust.

plural of two by four

(automotive) Abnormal operation of a two-stroke internal combustion engine, such that the cylinder only fires every second cycle (like a four-stroke engine). This occurs when the exhaust scavenging and inlet charging leaves a mixture in the cylinder which does not ignite, but needs a second scavenge/charge to produce an adequate mix.

(nautical) A boat, used in competitive rowing, having four rowers, each with a single oar / (rowing, especially in plural) A race in which such craft participate

Wide knickerbocker breeches, so called because originally they were designed with four inches of excess material so as to hang in a fold below the fastening beneath the knee; traditionally associated with sports, especially golf.

plural of petit four

having four doors

A motor car with four doors.