Antonyms of adj congenial

2 senses of congenial

Sense 1
congenial (vs. uncongenial) -- (suitable to your needs; "a congenial atmosphere to work in"; "two congenial spirits united...by mutual confidence and reciprocal virtues"- T.L.Peacock)

uncongenial (vs. congenial), incompatible -- (not suitable to your tastes or needs; "the uncongenial roommates were always fighting"; "the task was uncongenial to one sensitive to rebuffs")
        => disagreeable, unsympathetic -- (not agreeing with your tastes or expectations; "found the task disagreeable and decided to abandon it"; "a job temperamentally unsympathetic to him")

Sense 2
congenial -- ((used of plants) capable of cross-fertilization or of being grafted)

INDIRECT (VIA compatible) -> incompatible -- (not compatible; "incompatible personalities"; "incompatible colors")

Similarity of adj congenial

2 senses of congenial

Sense 1
congenial (vs. uncongenial) -- (suitable to your needs; "a congenial atmosphere to work in"; "two congenial spirits united...by mutual confidence and reciprocal virtues"- T.L.Peacock)
       => sociable -- (friendly and pleasant; "a sociable gathering")
          Also See-> compatible#1; friendly#1; sympathetic#2

Sense 2
congenial -- ((used of plants) capable of cross-fertilization or of being grafted)
       => compatible (vs. incompatible) -- (able to exist and perform in harmonious or agreeable combination; "a compatible married couple"; "her deeds were compatible with her ideology")