The Collaborative International Dictionary of English v.0.48:

Yogi \Yo"gi\, n. [Skr. y[=o]gin.]
   A follower of the yoga philosophy; an ascetic. [Spelt also
   yokin.] --Whitworth.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Yogi
    n 1: United States baseball player (born 1925) [syn: Berra,
         Lawrence Peter Berra, Yogi, Yogi Berra]
    2: one who practices yoga and has achieved a high level of
       spiritual insight

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "yogi":
   Albigensian, Brahman, Catharist, Franciscan, Ramwat, Sabbatarian,
   Trappist, Waldensian, abstainer, adept, anchorite, anthroposophist,
   ascetic, bairagi, bashara, bhikhari, bhikshu, cabalist, dervish,
   esoteric, fakir, flagellant, guru, hermit, mahatma, mendicant,
   mystagogue, mystic, pujari, pundit, puritan, purohit, sannyasi,
   supernaturalist, theosophist, transcendentalist, vairagi, yogin,
   yogist