The following are translations of the the second yoga sutra (I.2) – citta vritti nirodha –
“The restraint of the modifications of the mind-stuff is Yoga,” Sri Swami Satchidananda, The Yoga Sutras of Patanjali, 2003
“Yoga is the ability to direct the mind exclusively toward an object and sustain that direction without any distractions,” T.K.V. Desikachar, The Heart of Yoga, 1995
“Yoga is the control of thought-waves in the mind,” Swami Prabhavananda and Christopher Isherwood, How to Know God, 2007
“Yoga is the suspension of the fluctuations of the mind,” Gregor Maehle, Ashtanga Yoga, Practice & Philosophy, 2006
“We become whole by stopping how the mind turns,” Geshe Michael Roach & Christie McNally, The Essential Yoga Sutra, Ancient Wisdom for Your Yoga, 2005