Source : Webster's Revised Unabridged Dictionary (1913)

Hobo \Ho"bo\, n.; pl. {Hobos} or {Hoboes}. [Of uncertain
   origin.]
   A professional tramp; one who spends his life traveling from
   place to place, esp. by stealing rides on trains, and begging
   for a living. [U. S.] -- {Ho"bo*ism}, n.

Source : WordNet®

hobo
     n : a disreputable vagrant; "a homeless tramp"; "he tried to
         help the really down-and-out bums" [syn: {tramp}, {bum}]
     [also: {hoboes} (pl)]