Scaling

technically spoken

Scaling is often meant as Tracking a Source to fit and rescale to a destination.

most Synthesizer Manufacturers call that keytracking and refer to changing the Keyboard play in a different scale than the well tempered scaling, eg. if you spread the scaling to 200% if would allow 2 Octaves in the Keyboard to play the range of one, so the notes are not a half chromatic Note from each other but 1/4th but: it does not need to scale to the keyboard, it could scale Controllers or other parameters, too (technically spoken).

Musically spoken

there are different scalings (like eg. Microtuning allows to assign Notes differently to the Keyboard, so you will not play a well tempered scaling - chromatically but say arabian or Werckmeister scaling or others to choose from a preset list or create tables yourself).

see also: Hermode Tuning