gleaner

plural gleaners

1. One who gleans.
2. slangA person who focuses on self-improvement while in prison.

   Gleaners read, pursue formal education, may learn a trade through vocational education programs or job training, […]

   1976, United States. National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research, Research Involving Prisoners: Appendix to Report and Recommendations

   1 more example

   Release and renewal of life on the outside are the dominant concerns of time-doers and gleaners. Even jailers, although they tend to make prison life their central concern, are cognizant that they will return to the outside community.

   1987, John Irwin, The Felon, page 86