Not suitable to your tastes or needs:
— The uncongenial roommates were always fighting.
— The task was uncongenial to one sensitive to rebuffs.

synonym: incompatible.

Roget 657: insalubrious; unhealthy, unwholesome; noxious, noisome; morbific^†, morbiferous^†; mephitic, septic, azotic^†, deleterious; pestilent, pestiferous, pestilential; virulent, venomous, envenomed; poisonous, toxic, toxiferous^†, teratogenic; narcotic.    contagious, infectious, catching, taking, epidemic, zymotic^†; epizootic.    innutritious^†, indigestible, ungenial; uncongenial etc. (disagreeing) 24.    deadly etc. (killing) 361.    ... show more

Roget 24: disagreeing etc. v.; discordant, discrepant; at variance, at war; hostile, antagonistic, repugnant, incompatible, irreconcilable, inconsistent with; unconformable, exceptional etc. 83; intrusive, incongruous; disproportionate, disproportionated^†; inharmonious, unharmonious^†; inconsonant, unconsonant^†; divergent, repugnant to.    inapt, unapt, inappropriate, improper; unsuited, unsuitable; inapplicable, not to the point; unfit, unfitting, unbefitting; unbecoming; illtimed, unseasonable, mal a propos [Fr.], inadmissible; inapposite etc. (irrelevant) 10.    uncongenial; ill-assorted, ill-sorted; mismatched, misjoined^†, misplaced, misclassified; unaccommodating, irreducible, incommensurable, uncommensurable^†; unsympathetic.    out of character, out of keeping, out of proportion, out of joint, out of tune, out of place, out of season, out of its element; at odds with, at variance with.    ... show more

Very unfavorable to life or growth:
— An uncongenial atmosphere.
— An uncongenial soil.

synonyms: hostile, unfriendly.

Used of plant stock or scions; incapable of being grafted.