Source : Webster's Revised Unabridged Dictionary (1913)

Chipmunk \Chip"munk`\, n. [Indian name.] (Zo["o]l.)
   A squirrel-like animal of the genus {Tamias}, sometimes
   called the {striped squirrel}, {chipping squirrel}, {ground
   squirrel}, {hackee}. The common species of the United States
   is the {Tamias striatus}. [Written also {chipmonk},
   {chipmuck}, and {chipmuk}.]

Source : WordNet®

Tamias striatus
     n : small striped semiterrestrial eastern American squirrel with
         cheek pouches [syn: {eastern chipmunk}, {hackee}, {striped
         squirrel}, {ground squirrel}]