The opposite would be flexible. For an object, it could be ductile, bendable, elastic, or malleable. For a person, it could be amenable, accomodating, or receptive.
inflexible
Antonyms could include limited, inflexible, or unadjustable.
inflexible, unyielding, rigid, brittle
The opposite of a compromise would be a failure to compromise, possibly a stalemate (remaining in disagreement or unsettled).The opposite of the verb to compromise would be to not compromise, to be stubborn, adamant, or inflexible.
Two antonyms for flexible (meaning able to bend or adapt) are inflexible or rigid. Please see link for antonyms based upon different meanings for flexible.Fixed, inflexible, set, stiff, strict, and unbending are antonyms (opposites) to fexible.
My boss is very inflexible when it comes to changing our work schedule.
Kéraban the Inflexible was created in 1883.
I'm sorry, but this mandate remains inflexible.
Unlike a rubber band, a steel bar is very inflexible.
If something is inflexible, it cannot be easily moved or bent. If someone is inflexible, their opinions or decisions are usually solidly rooted in their minds and cannot be easily changed.
depends on the meaning you have in mind. In the meaning 'producing a good harvest / output' it would simply be 'not yielding', in the meaning 'giving in' it would be unyielding, stubborn, inflexible, pugnacious.
A scifi short story Absolutely Inflexible, by Robert Silverberg.