The ;J-command jumps to the beginning of a word. The complement of
this function (i.e. jump to the end of a word) does not exist as a primitive.
The following sequence fakes this function:

2 ;j
v0 ESC
< 1 u0 - c
  a ,  8 ;cEQ < -1 u0 >
  a , 10 ;cEQ < -1 u0 >
  a , 13 ;cEQ < -1 u0 >
  a , 32 ;cEQ < -1 u0 >
  q0 ; 
>
^0 ESC c ESC ESC

NOTE: if an error occurs, register 0 will not be properly popped.