A Yogi (also, Yogin; Sanskrit yogin-, nominative yogī; feminine: Yogini) is a term for a male who practices the path of Yoga, maintaining a steadfast mind, and engaging in the process of transcending the lower self. In contemporary English Yogin is an alternative rendering for the word Yogi. This word is also often used to describe Buddhist monks or any lay person or householder who is devoted to meditation.
The Shiva-Samhita text defines the Yogi as someone who knows that the entire cosmos is situated within his own body, and the Yoga-Shikha-Upanishad distinguishes two kinds of yogins: those who pierce through the sun (surya), by means of the various yogic techniques, and those who access the door of the central conduit (sushumna-nadi). 
By contrast, the Hatha Yoga Pradipika describes a yogi as a practitioner of seminal (bindu) retention, with the intention of absorbing the female essence (rajas) by means of the practice of the vajroli-mudra, also as a means of conscious conception practice.  
- Fuerestein, G. (2000). The Shambhala Encyclopedia of Yoga. Boston:Shambhala Publications.
- Swami Muktibodhananda Saraswati (Tr.) (1985). Hatha Yoga Pradipika. New Delhi:Thomson Press Ltd.