He argued that the design's unimprovability proved they shouldn't attempt any more revisions.

After years of refinement, she considered the design unimprovable.

Despite months of therapy, her unimproving condition worried the family.

The unimprovableness of her thesis impressed the entire committee, who struggled to find any substantive flaws.

The surveyor noted several unimproved lots behind the old mill.

Despite months of training, the team's unimprovement was obvious to the coaches.

Her performance was unimprovably precise, leaving no room for critique.