Simple may refer to:
- Simple (abstract algebra), an algebraic structure which "cannot be divided" (e.g., simple group, simple module, etc.)
- Simple extension, a field extension generated by the adjunction of a single element
- Simple function, a measurable function which takes on only finitely many values
- Simple graph, an undirected graph that has no loops and no more than one edge between any two different vertices.
- Simple harmonic motion, a type of periodic motion where the restoring force is directly proportional to the displacement.
- Simple path (disambiguation)
- Simple polygon, a polygon whose sides do not intersect
- Simple polytope, a d-dimensional polytope each of whose vertices are adjacent to exactly d edges (also d facets).
- Simple root (disambiguation)
- Simple set, a subset of the natural numbers that is co-infinite and recursively enumerable, but for which every infinite subset of its complement fails to be enumerated recursively.
- Simple rotations in higher-dimensional space
- Simple zeros and simple poles in complex analysis.
- The SIMPLE algorithm in computational fluid dynamics, a widely used numerical procedure to solve the Navier-Stokes equations
- Simple machine, a mechanical device that changes the direction or magnitude of a force
- SIMPLE, an instant messaging protocol
- SiMPLE, a programming development system
- SIMPLE (dark matter) (Superheated Instrument for Massive ParticLe Experiments), an experimental search for evidence of dark matter
- Simple, a steam engine that expands steam only once, as opposed to a compound engine that expands it more than once
See also List of people known as the Simple
- Simple Kapadia (1958–2009), Indian Bollywood actress and costume designer
- Simple Kaur, Indian weightlifter
- Michael Wharton, a newspaper columnist who wrote under the pseudonym Peter Simple in the British Daily Telegraph.
- Simple E, R&B singer whose 1994 single "Play My Funk", made the Billboard charts.
- Simple Kid (real name Ciaran McFeely), Irish-born solo musical artist.
- Simplé, a commune in the Mayenne department in north-western France
- Fort Simple, an American Civil War fort in Topeka Kansas