Cirrus may refer to:
In science:
- Cirrus cloud, a type of cloud
- Cirrus (rocket), a German research rocket
- Cirrus, a fleshy, downward extension of the upper lip in salamanders or fish
- Cirrus, a thoracic limb of an adult barnacle
- Cirrus (plural cirri), an unbranched appendage found in many invertebrate groups such as the Polychaeta and Echinodermata
- Cirrus (plural cirri), a tuft of fused cilia found in certain protozoa and used in locomotion
In the aviation industry:
- ADC Cirrus, a series of British aircraft engines in the 1920s
- Blackburn Cirrus Major, a British four-cylinder aircraft engine first run in 1936
- Blackburn Cirrus Minor, a British four-cylinder aircraft engine first run in 1937
- Cirrus Aero-Engines, a defunct British aircraft engine company
- Cirrus Aircraft, an aircraft manufacturer in Duluth, Minnesota
- Cirrus Airlines, a German airline in Saarbrücken, Germany
- Schempp-Hirth Cirrus, an Open-class sailplane
- Schempp-Hirth Standard Cirrus, a Standard-class sailplane
In other industries:
- Chrysler Cirrus, a car produced by DaimlerChrysler between 1995 and 2000
- Cirrus (interbank network), an interbank network by MasterCard
- Cirrus Logic, a semiconductor manufacturer
- Microsoft Jet Database Engine or Cirrus
In other uses:
- Cirrus (band), a duo of electronic music composers
- Cirrus (building), a high-rise apartment building in Helsinki, Finland
- Cirrus Vodka, a vodka made in Virginia, USA