modification
[C/U] Both
pl: modifications
This word carries a technical and precise connotation, suggesting a calculated adjustment rather than a total overhaul. It implies that the original structure remains intact, but specific elements are tweaked to optimize performance or fit a new requirement. In professional or legal settings, it is the preferred term for formal changes, whereas a word like "tweak" is too casual and "transformation" is too drastic. It evokes an image of a blueprint being carefully edited with a pen to refine a design.
Countable when referring to a specific change made to a thing (three modifications to the car). Uncountable when referring to the general process of altering something (the modification of the law).