Each group forms an arithmetic sequence of letters with step \(3\).
The directions alternate: \(+3\) (ADGJ), then \(-3\) (YVSP), then \(+3\) (KNQT).
So the next must be \(-3\):
\[
O\,(\!-\!3\!)\,L\,(\!-\!3\!)\,I\,(\!-\!3\!)\,F.
\]
\[
\boxed{\text{OLIF}}
\]