Wiktionary
n. A field of study or work that is related to one aspect, but not the whole, of a broader field of study or work.
Usage examples of "subdiscipline".
There is a mathematical underpinning that you musl first acquire, mastery of each mathematical subdiscipline leading you to the threshold of the next.
By the late 1950s, cybernetics was being superseded by the specialized technical fields and subdisciplines it had spawned, and Wiener himself wound up on the sidelines of his own revolution.
He knew that Nicholas was a ninja just as he knew that there was a whole range of subdisciplines in which Nicholas could be his sensei.
It was an exhausting business even for one such as he, for he knew by observing carefully that this particular dojo specialized not only in a myriad of arcane bujutsu subdisciplines involving the body but a number involving the mind as well.
Because so much telescope time had been freed when the signal from Vega had ceased, there was a beady air of progress in a dozen long-languishing subdisciplines of radio astronomy.