V4

V4 or V-4 may refer to:

Science and technology

 * LNER Class V4, a class of British steam locomotives
 * 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
 * ITU-T V.4, a telecommunication recommendation
 * 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
 * V-4 (rocket launch), first mostly-successful launch of the V-2 rocket

Other uses

 * Visegrád Group, an alliance of four Central European states - Czech Republic, Hungary, Poland and Slovakia
 * 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 (climbing) for difficulty of a boulder climbing route