patch

n. A diff (sense 2). 4. A set of modifications to binaries to be applied by
a patching program. IBM operating systems often receive updates to the
operating system in the form of absolute hexadecimal patches. If you have
modified your OS, you have to disassemble these back to the source. The
patches might later be corrected by other patches on top of them (patches
were said to grow scar tissue ). The result was often a convoluted patch
space and headaches galore. 5.

The term originates from the earliest digital computers which used paper
tape or punched cards in the 1940s. To fix a problem you would glue a
physical patch of tape or paper over the holes.