Terminology for the analysis of equine locomotion is reviewed and the most appropriate terms selected for use by research workers in this field. Each cycle of limb movement comprises a stance phase, when the hoof is in contact with the ground, alternating with a swing phase. The stance phase is subdivided at the mid-stance position into an initial decelerative phase followed by a propulsive phase. When the stance phases of different limbs occur concurrently, the term overlap refers to the duration of simultaneous ground contact. Single support is the term used to describe the phase when the limb is in its stance phase unaided by any other limb. A gait consists of a limb coordination pattern repeated at each stride. The start and finish of the stride must be designated as a prerequisite to the determination of stride length, stride duration and stride frequency. In asymmetrical gaits, such as the gallop, the stride as a whole will have a stride stance phase, when one or more limbs are in contact with the ground, and a suspension phase. In symmetrical gaits, such as the trot and pace, the stride consists of left and right stance phases and suspension phases. Advanced placement and advanced lift off measure the time between ground placement and lift off respectively of consecutive limbs. The line of motion indicates the progressive movement of the centre of gravity in the X-Y plane. Measurements in the Y-Z plane, such as line gait and overcrossing, describe the ground placement of the hooves relative to the line of motion. Diagonal width is the distance between diagonal limb pairs in this plane.