Definition of fishtailed:
(n) :
The tail of a fish, or an object resembling this.
(n) :
The skidding of the back of a vehicle from side to side.
(v) :
(intransitive) To swing the back of a vehicle (originally an aircraft) from side to side.
(v) :
(transitive) To cause the back of (a vehicle) to swing from side to side.
(v) :
(intransitive) To move with the tail swinging from side to side in this way.
(n) :
A kind of chisel with a flared blade.