Both Uses

congenial
in
Heart of Darkness
(Auto-generated)

Brought from all the recesses of the coast in all the legality of time contracts, lost in uncongenial surroundings, fed on unfamiliar food, they sickened, became inefficient, and were then allowed to crawl away and rest.†
Chpt 1 *

uncongenial = not agreeable or compatible

standard prefix: The prefix "un-" in uncongenial means not and reverses the meaning of congenial. This is the same pattern you see in words like unhappy, unknown, and unlucky.
However, they were all waiting—all the sixteen or twenty pilgrims of them—for something; and upon my word it did not seem an uncongenial occupation, from the way they took it, though the only thing that ever came to them was disease—as far as I could see.†
Chpt 1

Definitions:

(1) (congenial)
agreeable or compatible in a positive way -- often in the context of being friendly and sociable
(2) (meaning too rare to warrant focus)