WordWeb Online

1. Very unfavourable to life or growth
   "an uncongenial atmosphere";
   - hostile, unfriendly
    
2. Used of plant stock or scions; incapable of being grafted
    
3. Not suitable to your tastes or needs
   "the task was uncongenial to one sensitive to rebuffs"; "the uncongenial roommates were always fighting";
   - incompatible

See also: disagreeable, incompatible, inhospitable, unfriendly, unsympathetic