A Yogi is a practitioner of Yoga. The word is also used to refer to ascetic practitioners of meditation in a number of South Asian religions including Hinduism, Buddhism, and Jainism.
The word Yogi (Sanskrit: masc yogī, योगी ; fem yoginī) originally referred in the Classical Sanskrit of the Puranas specifically to a male practitioner of Yoga. In the same literature yoginī is the term used for female practitioners as well as divine goddesses and enlightened mothers, all revered as aspects of the Divine Mother Devi, without whom there would be no yogis. The two terms are still used today but the word Yogi is also generically used to refer to both male and female practitioners of yoga and related meditative practices in Buddhism, Jainism, Taoism etc.
The word is also often used in the Buddhist context to describe Buddhist monks or a householder devoted to meditation.