V4

V4 or V-4 may refer to:

Science and technology

• LNER Class V4, a British steam locomotive
• V4 engine, a V engine with four cylinders in two banks of two cylinders
• Visual area V4, in the visual cortex
• Klein four-group, in mathematics
• V.4, an ITU-T recommendation for data transmission
• ATC code V04 Diagnostic agents, a subgroup of the Anatomical Therapeutic Chemical Classification System
• The V4 JavaScript engine for QML
• V₄, one of six precordial leads in electrocardiography

Other uses

• Visegrád Group, an alliance of four Central European states
• Rheinbote or V-4, a German World War II four-stage missile
• Saint Kitts & Nevis (ITU prefix)
• Vieques Air Link (IATA airline code)
• V4, a grade for difficulty of a boulder climbing route