Definition

1. Noun:
   • An internal combustion engine that completes its power cycle in four distinct piston strokes (intake, compression, power, and exhaust) within a single thermodynamic cycle. It is the most common type of engine found in cars, motorcycles, and many other vehicles.

Usage Examples

• Noun:
  • Most modern cars are powered by a four-stroke engine.
  • The efficiency of a four-stroke engine is generally higher than that of a two-stroke design.
  • He is learning how the valves operate in a four-stroke engine.

Advanced Usage

• "four-stroke cycle": The sequence of operations (intake, compression, power, exhaust) that defines the engine's function.
  • Understanding the four-stroke cycle is fundamental to automotive mechanics.
• "four-stroke principle": The underlying thermodynamic and mechanical theory of the engine's operation.
  • The four-stroke principle was patented by Nikolaus Otto in 1876.

Variants and Related Words

• Four-stroke (adjective): Describing something related to or operating on this principle.
  • Four-stroke motorcycles require specific oil.
• Four-cycle engine (noun): A synonymous term, commonly used in American English.
• Otto cycle engine (noun): A technical synonym named after its inventor, Nikolaus Otto.

Synonyms

• Four-cycle engine
• Otto engine

Antonyms

• Two-stroke engine (an internal combustion engine that completes a power cycle with two piston strokes).

Noun

1. an internal-combustion engine in which an explosive mixture is drawn into the cylinder on the first stroke and is compressed and ignited on the second stroke; work is done on the third stroke and the products of combustion are exhausted on the fourth stroke