RELAX/RELAXATION – 1.Referring to the horse’s mental/emotional state: calm, without anxiety or nervousness.
2. Referring to the horse’s physical state: commonly used to indicate the absence of muscular contraction other than that needed for optimal carriage, strength, and range and fluency of movement.
Usually the physical and mental/emotional states go hand in hand.
Full glossary: http://bit.ly/2019USDFGlossary